Hello and welcome to ESPNF1's live coverage of the opening free practice session from the brand new Circuit of the Americas. It's a slightly chilly morning but it's sunny and clear in Texas for the first session in the United States since 2007.

There's been a lot of talk about the circuit and Formula One's return to America, but in 25 minutes the talking will stop and the drivers will get their first taste of the track. Simulators can only tell them so much.

I said it was a bit chilly; it's actually only 12C with the track temperature at 16C. Air temperature is expected to peak at 20C today but that won't be until later in the day, as we're starting early this morning.

In fact, we're starting so early that Laurence was in the paddock to see the sun rise over turn one today:

© Laurence Edmondson

There will be plenty of talking points this weekend, and I'm sure you'll all want to add your thoughts. We especially want to hear from fans in the US; how's the reaction been to Formula One arriving (if there has been any reaction) and how excited are you for this weekend? You can either email us using the link above or tweet us @ESPNF1

@chicho_salazar on Twitter says: "I used to live in Austin and waiting for this race since it was announced .. lots of latin people like me excited to be there"

There's been a lot of talk surrounding turn one - which does look interesting - but I must admit my main interest is in the last sector. It could help bunch the cars up, or it could be a bit mickey mouse. Hopefully turns 16, 17 and 18 (the triple apex right hander) will prove to be a real challenge. What are your thoughts?

Rahulan emails in to ask: "Green track, what is the term used for? I heard it for the first time during the Indian GP. I'm assuming a track without any grip is called that way. So Austin also comes into that bracket?"

Exactly Rahulan. A green track is one with little rubber on it, so it has less grip and is therefore slippery and lap times are slower.

Before we get under way, the only driver change for this session is Ma Qing Hua in for Narain Karthikeyan at HRT

A bit of an historic moment this; the first man out on track is Kimi Raikkonen and the session has begun!

Mario Andretti strolls down the pit lane as the cars head out on track

Glock has already had a moment on his out lap, running off track at turn four having almost lost the rear

Massa radios in to say "It's very, very slippery, the track. Very slippery"

Massa is the first man to start a lap as he continues after his installation lap. He's got flo-viz paint on the rear wing of his Ferrari

Matt emails in to say: "Loved Mark Webber's comments about the black things on the corners - that's just cheeky Aussie humour for anyone elsewhere in the world who thinks he was a bit crass! Sending from Hobart, Tasmania, Australia @ 2am local time."

Webber said "If the black things in the corners aren't working then you can put the layout up your arse - the car's not going to work" as he emphasised the importance of tyres this weekend.

And great commitment, Matt!

Hulkenberg says on the radio: "It's very slippery, it's worse than rain"

Hamilton the only man on track now as he does a second installation lap too

Debbie emails in to say: "Really looking forward to the race. Couldn't afford to go this year since we went to Montreal but hopefully next year we'll get there. I'm in Connecticut. Hopefully New Jersey will happen too, then we can just take the train in. So excited to see F1 back in the states.

GO KIMI !!!!!!!!"

Rahulan asks: "What downforce levels will be cars be setup for this race? Will the engineers come to know only after the cars run on the track or will the simulators would have given them enough evidence for setups?"

It's a medium downforce circuit as there's a real mix of high speed and low speed corners (six of each) plus the long main straight added to the quick opening sector. The teams will have known thanks to their simulations, but drivers are likely to find it tough to finalise their set-ups

Another reason the drivers are struggling for grip is because they're using hard compound tyres here, and they have an extra set of the hard tyres for today to help the teams learn the track

Schumacher returned to the pit lane with a bit of smoke out of the rear of his car earlier. Mercedes is doing a lot of work on exhausts this weekend with Ross Brawn revealing yesterday that Rosberg is not running the Coanda exhaust in this session so that the team can compare data with Schumacher who is running the Coanda exhaust

Nicolas emails in: "Was it raining yesterday? Why is the track so slippery?"

The track is so slippery because it's not been used yet, so there's no grip because there's no rubber on the track surface. It's simply a result of a new circuit.

Kobayashi sets the first timed lap, and it's a 1:54.846. To give you an idea of how slippy it is, Mercedes thinks a pole time will be around a 1:37.000

Kobayashi lowers that to a 1:51.228, while Raikkonen does a 1:54.902 and Senna a 1:56.291

The drivers are at nowhere near 100% at present as they tiptoe around

Times are dropping fairly quickly as Kobayashi does a 1:48.517

Bob emails in from North Carolina to say: "I never thought I'd get this excited, but I am. A new circuit in the USA, who would of thought. And-a great battle for the championship."

Tom emails in from California to ask: "Are there spectators and if so, how does the spectator count look?"

There are plenty of fans around for a Friday practice session. The grandstands are largely empty but there are people in each one and a number on the grass banking areas too

Kobayashi has just run off at turn 16, sliding wide as he starts to push harder. He's still quickest with a 1:46.960

Abhishek emails in from India: "What procedure do the team follow in replacing one of their drivers with the reserve driver in FP1?? More sponsors??"

They have to request the change with the FIA (and subsequently request the change back to the race driver after FP1), and sponsorship exposure appears to be the driving force for Ma at HRT this weekend, but others are to help drivers gain experience ahead of a potential future race seat

Both Red Bull's on track and Webber has gone second on a 1:45.918

Remy asks: "How do they look through the first corner? And which corners are banked the wrong way?"

Turn one looks fairly normal at this stage, though we've seen many drivers lock up and miss the apex. The real test of that corner comes in the race. It looks like the final sector features the off-camber corners.

Webber goes quickest with a 1:44.237

Vettel runs wide at turn 19 as he goes fourth quickest with a 1:46.240

The only teams we are yet to see since the installation laps are HRT and Marussia...

Marcus asks: "Is there any indication how many laps have to be done to run the track in prior to setting really indicating times there or is it more about "it's getting better every lap of the weekend"?"

It really is a case of constant track evolution, Marcus. Nico Rosberg's race engineer has told him over the radio that he believes a lack of grip will just be a feature of the weekend

Mehul asks about Ferrari updates; all of the teams will be bringing updates and testing new parts this weekend, but few are likely to say what they are. Appears to be a modified rear wing as Massa is running flo-viz paint on his rear wing to analyse how the airflow passes over it

Webber improves to a 1:43.672 and Vettel is now second - 0.5s back

Hamilton goes quickest by a second with a 1:42.603. We're already 12 seconds faster than Kobayashi's opening lap

Andre from Florida asks: "First of all I would like to say that its good to see the USGP back, but anyhow my question is, could the lack of lack rubber on the track have any real effect on qualifying?"

Yes it could Andre, but by that stage it is likely that mistakes will be punished heavily as it will still be very slippy off-line, but not so bad on the racing line

Hamilton now quickest with a 1:40.918 ahead of Nico Rosberg on a 1:42.131

Alonso goes second with a 1:41.365

We had a brief yellow as Nico Hulkenberg spun at turn one. A case of the car going light as it crests the hill coupled with a lack of grip

Madhan asks about live timing issues - we're unsure why but live timing isn't working at present. Fortunately we have a back-up timing screen here, and another back-up in the form of Laurence in the media centre!

Hulkenberg with another spin at turn 13, while Perez almost ends up in the wall as he approaches the pit lane a bit too quickly

Shane emails in to say: "I'm really excited to see how the driving and tactics evolve for turns 15-19. Turn 15 after the straight followed by the wide turns of 16-18. Then they have to set up for a sharp turn 19... Wondering how they will tackle that wide turn followed by the short straight to 19."

This is exactly the area I was talking about earlier, which is proving tricky with the lack of grip at present

Alonso has gone quickest with a 1:40.603 ahead of Hamilton and Button. Rosberg in fourth is 1.5s off the pace

Scott emails in from New Jersey: "As the cars scrub the loose fine aggregate from the track surface, the grip level will quickly improve. The tire wear found in this FP1 will be of little use for the engineers. Thanks to Pirelli for providing an extra set of the 'black things'. Do you feel this rapid grip improvement is similar to the inaugural FP1 at Abu Dhabi and New Dehli? Some of the drivers will all have instances that may require a change of shorts before today's session's end. Hope to see both Texas and New Jersey on the 2014 calendar."

The problem with India was that the track was very dusty, which is similar to here too, so I think it will be similar to that circuit. I'm recalling this off the top of my head but I believe Abu Dhabi had seen action from a support series before F1 arrived there, so it was less of a problem at Yas Marina

Hamilton and Vettel run wide at turn 19. Vettel, of course, has a new helmet design for this weekend...

Puxan asks: "Will the lack of support series have a significant impact on grip levels throughout the weekend? How much does the driver make the difference in these low-grip and new circuit configurations?"

There's a Ferrari support series but that's it, so the Formula One running will be crucial to grip levels. The driver makes the biggest difference with the slippery surface similar to how it is when it's wet, but they'll all pick up the configuration quickly

Hamilton returns to the top of the timesheets with a 1:40.175. All of the running in FP1 will be done on the hard tyre.

Ma Qing Hua has completed eight laps now for HRT with a best of 2:03.263, but still no sign of de la Rosa since his installation lap

John asks what the predicted single lap time will be here; Mercedes said it was looking at the pole time being around a 1:37.000

Henry emails in to ask: "Have you spoken to any of the drivers today? I know it is still early but any predictions?"

Not been able to speak to the drivers yet - we get that after FP2 but Laurence will chat to Christian Horner after the first session - and the prediction I went for in the preview was for Hamilton to win. He's currently 0.353s clear of Button and the rest of the field, so looking good so far!

De la Rosa has now gone back out. Ten laps for HRT so far; less than any other driver has completed on his own. I'm mentioning this as reports in the Spanish press before the weekend suggested that the team did not have enough spare parts to run safely this weekend

Aravind asks: "Are Raikkonen and Maldonado not doing any timed laps? Or are their lap times really that bad right now?"

Raikkonen is on a timed lap at present, but there's a big field spread as drivers build up confidence and test updates for their teams

Rosberg has improves his best time but is still 1.2s off the pace in fourth place

Tim emails in to ask: "Where will the overtaking take happen on this circuit?"

Turn one will give opportunities as it's very wide and the gradient allows late braking, while in to the turn 11 hairpin is similarly wide to encourage a move. The best opportunity though comes at turn 12 after a long, undulating straight where the DRS will be located

Kobayashi goes fourth with a 1:41.036

Turn 19 appears to be a real challenge for a number of drivers, with plenty running wide

De la Rosa has set a time which is 17.4s off the pace after six complete laps

Rosberg improves in fifth place and is just under a second slower than Hamilton

Constant speed test being carried out by Massa down the 1.2km straight

Vettel's gone fourth with a 1:40.978

John asks: "How high is turn 1 from the start line - there's a picture showing it looks like a mini-mountain!"

It's just over 130ft up, or 40 metres. So it is a mini-mountain!

Alonso is pushing hard and after looking spectacular through the first sector he's almost half a second up on Hamilton. The change of direction through there is awesome

Vettel's gone second with a 1:40.335 - just 0.160s slower than Hamilton

Alonso improves to third quickest; he's 0.162s slower than Hamilton and just 0.002s off Vettel's best so far

Abhishek asks: "Why only one driver always has to compensate his drive in FP1? Like Senna and not Maldanado, Narain and not de la rosa!!"

It's part of the drivers contract, so one driver might have it that it says he can't be replaced in Friday practice sessions (de la Rosa can demand this due to his experience and Maldonado his money), whereas the other drivers were in weaker bargaining positions when they signed deals

Hamilton improves his best time to a 1:40.116. He seems to settle quickly on new tracks

Kovalainen with a spin at turn ten, which is blind and will not have been a comfortable place to stop

Hamilton improves once again and is the first man below the 1m40s barrier with a 1:39.687

Webber with a spin at turn eight. Still tricky out there

Button rejoins with exactly ten minutes of the session to go. He's 0.841s off the pace at present

Siddhesh says: "Interesting what you said earlier on Michael running the Coanda exhausts in this session while Nico has reverted to the old exhaust. Given the current timings, is it actually possible that Mercedes's upgraded exhausts are slower than the old spec ones?!"

The different exhausts require a different driving style, especially in terms of corner speed and throttle application. So with the track slippery the Coanda may not be quite so effective at present

Hamilton improves again by a further 0.017s

Paul emails in to ask: "On a new track that nobody's driven, why would HRT not want their race driver in the car on Friday to learn the track as best possible?"

The short answer is money, Paul. Ma has Chinese sponsors that can be exposed, and the team is currently up for sale and struggling for money

Hamilton once again lowers the best time to a 1:39.543 and is now 0.8s clear of the rest of the field

Glock has some flo-viz paint on the Marussia nose cone and he's just improved his best time but is still 5.4s off the pace

Shane emails in from Austin to ask: "I heard that the drivers are calling the lead up to Turn 1 and Turn 1 "The Wall." Any validation of that?"

Not that we've heard, Shane. But Kobayashi was funny when talking about turn one, saying it was "nothing special" for him

Vettel goes comfortably quickest with a 1:38.692

Only Grosjean and de la Rosa not on track with two minutes remaining

Vettel has a lot of flo-viz paint on the inside of his front left tyre (so presumably coming off the front wing) and it appears to be working with the pace he's showing

Marc asks: "Do you have any links for pictures of the special helmet Vettel is using for this GP?" We will have one on the site as soon as the session ends

Chequered flag is out and Vettel is improving again...

And Vettel improves to a 1:38.125. That leaves him 1.4s quicker than the rest of the field. Hmmm.

Raikkonen is stopped at the end of the pit lane and climbing out of his car. Could have been that the light had gone red to stop him joining the track.

Abhishek asks: "What difference does Flow Visualization paint make?? What is it actually?"

It makes no difference to the pace of the car, but shows the teams how the air is flowing over certain parts of the car in order to allow them to analyse new parts

Looks like a bit of a leak on Webber's car with some fluid running off the side of the sidepod

While Vettel is dominant in terms of the gap at the end of the session, don't forget how close it looked before then and Hamilton didn't set a time in the last five minutes. The top six places are filled by Red Bull, McLaren and Ferrari, however, so it certainly looks like being the usual suspects this weekend.

That concludes our coverage of FP1, make sure you stay with ESPNF1.com for the report and pictures ahead of FP2. We'll be back with live commentary in two hours' time. Bye for now.