Morning everyone, and welcome to ESPNF1's coverage of the first free practice session ahead of Sunday's Spanish Grand Prix. It's a warm and sunny day just outside Barcelona, where the whole grid will have one aim: Stop Sebastian Vettel.

Well, it won't be the whole grid with that aim. With updated cars the midfield will be hoping to leapfrog one another, while Lotus look to join the party, and Virgin and HRT battle it out at the back.

There are a lot of updated cars that need to be looked at today, with McLaren, Force India, Williams and Lotus talking up their respective upgrades prior to the race. The teams have a lot of data to reference against, having tested extensively at the circuit during the winter.

And we're about to find out who is looking in the best shape as the green light is on at the end of the pit lane. Heikki Kovalainen is the first man out.

If you want to get in touch with us during this 90 minute session you can do so using the link at the top of this page, or via Twitter @ESPNF1_live

The driver changes for this session see Daniel Ricciardo in for Sebastian Buemi at Toro Rosso and Nico Hulkenberg in for Paul di Resta at Force India.

Rubens Barrichello leaves the pit lane for Williams with some aero paint on the new rear wing that he is testing.

Roland asks: "Will Michael Schumacher stop racing end of this season? Does he still have what is right to win the championship?"

Whether he stops at the end of the season is open to debate - Mercedes are unlikely to push a seven-time world champion so it will be down to if he feels he can't compete at this level anymore. As it stands he doesn't have the most fundamental thing required to win the championship and that's a race winning car.

Felipe Massa sets the first timed lap of the race weekend - a 1:47.387

Ian emails in his opinion on one of the changes for 2011: "I'm still not sure about the new tyre rules. It seems to me that stronger teams are looking at ways of saving good tyres for the race. This is especially true during qualifying, very evident at the last race with Vettel and Webber sitting through the last part of qualifying whereas the lower teams have to eat up soft tyres in qualifying. It would also be interesting to see how many practice laps have been done this year as compared to last year.It's always been my feeling that, as there are no points for qualifying, then everyone should start the race with an equal number of NEW tyres and an equal number of both types."

Force India (clubforce) on Twitter: "As usual install laps and radio checks kick off the day in BCN. In terms of tyres we will stay on the hards for the entire morning."

The hard tyre this weekend is different to the compound used at previous races, it has been tweaked to last a few laps longer.

Nizam asks: "Do you think that the 2011 rule changes will encourage more overtaking in Barcelona - which had traditionally been a rather processional race?"

Looking at the races we've had so far this year Nizam yes I do. The DRS zone is the longest it has been so far, which should allow cars to overtake at speed, but the biggest differential comes from the tyres, and it doesn't really matter where you are on the track - if your tyres have gone off you are going to get overtaken.

Schumacher sets the fastest time with a 1:33.513, with Rosberg 2nd on a 1:40.962. They've both done five laps.

Only Kobayashi and Perez on track at present.

Karthikeyan joins them as Sergio Perez completes his lap and goes quickest so far with a 1:30.589.

Lewis Hamilton heads out on to the circuit to see how the McLaren updates are working. The most obvious change is a neater rear end, although that is more a tidying up job rather than an attempt for a huge gain in lap time.

It doesn't appear to be helping straight away, as Hamilton locks up his front right and runs wide on the exit of turn 13. Kobayashi and Perez are trading fastest times at the top of the timesheets, with Perez's 1:28.112 currently ahead of Kobayashi's 1:28.843

Hamilton muscles his way past a slow Narain Karthikeyan as Perez does a 1:27.512

Hamilton radios in with some sort of issue and is told to pit.

Luthando says: "I have to say that as much as I appreciate the increased spectacle it does become confusing while watching the race. It becomes hard to follow the leaders and any action in the midfield during the race, basically I can't follow the race beyond the top 5 until the last few laps. I appreciate the tyres and I would hate for them to go, but the DRS is too much icing on the cake for me."

Despite that message for Hamilton, he continues and sets the second fastest time: a 1:27.948

Timo Glock exits turn nine and starts going very slowly. No major dramas though as he contines to start another lap. A lot of data needs to be gathered, so drivers carry out constant speed tests.

Nigel asks: "One of the most impressive drivers this year has been Kobyashi. The last race, had it not been for a puncture, he would have been in 7th place...after starting in 24th! What are the chances you see for such a real 'racing' driver getting into a top flight car?"

As you say, Kobayashi was very impressive in Turkey, and has had a strong start to the year. Sauber have an engine deal with Ferrari and the early talk was of Sergio Perez being groomed for a seat there, but they won't be ignoring Kobayashi either. Having signed a new five-year deal though, Fernando Alonso probably has a big say on who his potential team-mate will be.

Jenson Button goes fourth quickes with a 1:29.318, and Maldonado fifth on a 1:31.958

Button improves to a 1:27.516, just 0.004s off Perez's headline time.

Steve asks: "How many times this season have we seen Daniel Ricciardo beat his more senior team mate in practice? Do you think he'll do it again today?"

He may well do so Steve, but what you must remember is he isn't setting a car up for the race in the same way his team-mate is, so while he will be carrying out work for the team you can't really compare the times between the two.

Mark Webber is out on track, as we hear that Lewis Hamilton is having his right rear brake cylinder changed.

Webber goes fastest with a 1:27.075. He's been strong at Barcelona in recent years - dominating in 2010 with pole and the race win.

Virgin (MarussiaVirgin) on Twitter: "Timo in now. These runs are mainly about collecting aero data."

Virigin are testing a new exhaust system, which was unreliable in Turkey and not used in the race.

Webber lowers the target time by some way, going round in 1:25.473. Jenson Button is now 2nd with a 1:27.138.

Felipe Massa is as busy as ever. He's the first man in to double figures in terms of laps, currently 7th with a 1:28.654

Michael Schumacher gets out of shape in turn five but manages to correct the car. Mercedes also has new updates, with Ross Brawn telling us earlier this week that it will be being fairly ambitious with its car development.

Webber improves to a 1:25.142. Schumacher went fourth with a 1:27.921 and Vettel eighth with a 1:28.606.

We've had an email asking: "Drivers can use DRS if the gap is below 1s. Can both drivers use this DSR or the back driver only (who's going to overtake)?"

It's just the driver behind that can use the DRS, otherwise the system would be ineffective. All drivers can use the DRS whenever they like during practice and qualifying, though.

Alguersuari locks his front right on the way down to turn ten. He's 13th quickest at the moment.

Vettel has improved to a 1:26.600 and second quickest, but has pitted with a sensor problem.

Neville asks: "As a result of frequent testing at this circuit the most recent races have been boring affairs. This weekend should be the ultimate test of kers, Pirelli and DRS surely?"

It will be Neville yes. The drivers have said that if the new rules lead to overtaking and an exciting race here then they will work anywhere.

Nico Rosberg goes third fastest - a 1:26.685

Of the two drivers who are driving this morning but not racing on Sunday, Hulkenberg is 10th for Force India and Ricciardo 11th for Toro Rosso.

Thanks to Thomas for spotting a Rosberg typo! My wrists firmly slapped.

Robbie asks: "As a keen Webber fan, I'm wondering why Webber is so far off the pace to Vettel, given how close they were last season? No doubt Vettel has immense talent, but why is the gap so big this year (particularly in qualy)?"

Webber appeared to have the poor luck earlier in the season, but he admitted that Vettel just didn't make any mistakes in qualifying in Turkey, and that he would have to drive a faultless lap himself to beat him. Vettel is in great form at the moment, but this could be the weekend when Webber finally closes the gap to him.

Speaking of Nico Rosberg, he's improved to a 1:26.379 to go second. Felipe Massa is having his front wing endplates changed in the pits.

Hans asks: "Apart from DRS and tyres the cars are minimally different from 2010. How is it that so many updates can be introduced? Surely at some point the car is optimized and only needs to be tweaked for the characteristics of a track. Or are the advances in aerodynamics, suspension or exhausts so fast that in a matter of days or weeks a new development emerges?"

A lot of small changes are implemented each year in order to prevent the cars becoming too fast, so teams push to find a bit of time in any area. As you say there are also lots of other areas of development, and each one will have an effect on the other.

Oops. Pastor Maldonado runs a bit wide in turn 12 and slides off in to the gravel. He keeps the car out of the barriers but beaches it and steps out of the car.

Vitaly Petrov had just said "These tyres are like ice, it's very difficult to warm them up" over the radio. That could have been the course of Maldonado's frankly quite embarrassing off.

Mark Webber uses his DRS to pull alongside Jenson Button on the pit straight, and outbrakes him nicely in to turn one. Who said there's no overtaking here?!

InsideFerrari on Twitter: "Felipe and Fernando have two different technical programmes with different solutions fitted on their cars."

Sebastian Vettel has been told not to use KERS. Could the gremlins be creeping back in for Red Bull?

Dave asks: "What's happened to Glock?"

There was an odd situation when it said Glock had stopped out on track, but he was actually sitting in the garage. Virgin were trying to cool the exhausts again though and had the engine cover off.

Neville says: "Since Vettel won the title it has been as if he has felt a release in pressure and his driving shows as much. Reminiscent of Schumacher in 02, 03 and 04. It will be hard for any team mate to match him."

Vettel improves to a 1:26.149, still a second slower than Webber at present.

A lot of work going on around Lewis Hamilton's car at the moment as he sits in the garage. Teams are making changes all the time trying to get the most out of any updates.

Rosberg gets a radio message telling him to "Boost, boost, boost", which we'd expect is in reference to his KERS.

Alonso is fourth at the moment, a 1:26.480, while Massa's different schedule means he's only 15th quickest.

Kovalainen is just 0.2s off the pace of Sutil in the Force India, and within half a second of Massa. Having completed 15 laps it looks like Lotus is getting some performance from its new exhaust system.

Paul Hembrey is an interested onlooker from Pirelli, as many drivers have been complaining of low grip on the new hard compound.

Hamilton is one of 11 cars out on track now, currently fifth fastest. He's nowhere near full throttle through turn three, which could be due to a heavy fuel load or a combination of little grip from the track at this early stage of the weekend and the hard Pirelli tyres.

15 minutes left in the session, and Nico Rosberg is currently the busiest man having completed 23 laps.

Some front wing analysis shows the Red Bull front wing skimming the track through turn 9, while McLaren's is much higher. Ferrari, Mercedes and Renault are somewhere in between.

HRT have some new rear wing elements as well as other updates, and Narain Karthikeyan has completed 22 laps trying to evaluate them. He is currently slowest by 0.7s though.

Fastest man Webber is back out on track, with the Red Bull looking very well planted changing direction through the quick first three corners.

Liuzzi is sat in his car in the garage, but a lot of the bodywork is off and he won't get too many laps in with 9 minutes left.

Rubens Barrichello has said that Williams need to finish in the points this weekend, and he's currently an encouraging ninth.

Alguersuari's session is over, with Toro Rosso saying it's an engine problem. He's only completed nine laps this morning.

Anthony asks: "With such a long DRS section for this event, if a driver makes a pass early in the DRS zone, can the passed driver then activate his DRS and fight back straight away?"

No Anthony they can't, only the following car can do so.

Chris asks: "Are F1 teams limited to just 2 drivers?"

They're limited to running two cars Chris, but they can have as many drivers on their books as they want. If they want to change their race drivers then they need to have that change approved by the FIA before the race weekend.

A busy end to the session, with 19 cars out on track.

Perez has improved to a 1:26.954 and fifth place.

On board with Sebastian Vettel, and he seems to be running with a heavier fuel load. He's also still not using KERS.

As the flag drops, Webber gets told to "use the KERS toggle for turn ten", so no such problems on the sister Red Bull.

No late movers, as Webber finishes the session with the fastest time, a 1:25.142. He's a full second quicker than his team-mate Vettel on a 1:26.149. Rosberg is third on a 1:26.379, 0.1s ahead of Alonso in fourth and Perez is a further 0.2s back in fifth.

Hamilton was sixth for McLaren with a 1:26.988, just ahead of Schumacher, Heidfeld and Button. All four are seperated be just 0.150s.

Mike Gascoyne on Twitter gives a bit of feedback on the new Pirelli hard compound: "Tyres difficult to handle in that session. The new hard tyre went off very quickly. Jarno had to change power steering in the session"

The busiest man? Michael Schumacher completed 32 laps, which shows that mileage was more important than headline times. Thanks for joining us and for all of your questions, make sure you're back again for second practice in two and a half hours. See you then.