Hello and welcome to the third and final practice session ahead of qualifying for the Spanish Grand Prix.

The Red Bulls looked quick yesterday but its worth keeping an eye out for the McLarens and Ferraris as well as Michael Schumacher who appeared to have a return to form with the updated Mercedes.

There was rain overnight again but the bad weather is holding off at the moment. Very mixed forecasts for the next two days so anything could happen.

The drivers are getting into their cars ready for the start of the session. Expect to see some quick laps over the next hour as the drivers tweak their set-ups for qualifying.

As always if you have any questions or want to make any observations, you can send them through by clicking here.

Lots of focus on the Mercedes garage today after a great couple of session for Schumacher yesterday. Rosberg said he took the wrong route with set-up and insisted the new Mercedes is to his liking despite his slower times.

So the cars leave the pits, Trulli leads the way in the Lotus.

Lots of cars heading out. Chandhok told the circuit will be "green" (have less grip) after last night's rain.

Ferrari says: "FP3 has just begun: both Felipe and Fernando are running their respective installation lap."

A question from Gary: "Do you think the Ferrari F-duct is giving the F10 an improvement?"

We've had conflicting reports on that. I don't think it is working as they would like and they said they would evaluate it last night. When I see a picture of the car I'll let you know if they are running it. If it isn't working well, it won't be on the car.

All the cars bar the Mercedes have put in an installation lap and are coming back into the pits.

Force India's plan for the next hour: "Both drivers have completed install laps, on the menu today is tyre comparison and prep for qualifying."

Omer asks: "If the HRT is as fast as the McLaren in a straight line, why is it 6 seconds off the front-runner? Is it because of the driver or the car's handling?"

Exactly that. We saw some pictures yesterday of the HRT looking very out of shape under braking. Fundamentally it is lacking a huge amount of downforce and that is so crucial at this track.

The HRT was the second fastest car through the speed trap yesterday for those wondering, second to McLaren.

Suzi asks: "We have been informed about Alonso's use of 3 engines so far this season. Does anyone know how many engines the rest of the top 4 teams & drivers have used?"

I don't know for certain but I think most of them would have also used about three engines. The big difference is that two of Alonso's have blown up so he won't be able to use them again in free practice at coming races.

No laps completed yet but Hulkenberg is out on track.

For those asking, FOM don't allow us to put up live lap times from the track. What I can tell you, however, is that Hulkenberg's first lap was a 1:24.378.

Milan: "Interesting to see that Klien was half a second quicker than Senna in yesterday's practice. That doesn't looks good for Bruno at all."

I agree, Senna was then beaten by Chandhok in second practice, so I guess he's not having a great weekend.

Mercedes says: "Some heavy overnight rain in Barcelona so the drivers are just being advised that the kerbs might still be a little damp..."

Chandhok is still struggling with that HRT under braking.

Kobayashi and Petrov in the gravel in separate incidents I think. Red Flag, Petrov's Renault is in a bad way, he's lost his rear wing.

Watching the replay it looked like some kind of failure at the back of the car and the car snapped away from Petrov.

Meanwhile, Kobayashi had a similar problem at the same corner (turn 4) and slid into the gravel. No damage to the Sauber but that could be the end of his session.

So Renault will have to repair that car before qualifying, just like they did in China.

The marshals are sweeping rain out of the kerbing which could explain why the drivers lost the rear of the cars when they ran over them.

Petrov's car has damage to the rear, the right side pod and the front wing. So defintely wet kerbing causing those accidents as replays show water spraying up from them as the cars went over them.

Before that accident Kobayashi was quickest on a 1:22.436, but that time will be beaten pretty quickly as the session restarts.

Nigel says: "Why is Mr. Alonso such a sour competitor? What is it about his psychology which makes him that way? The only other one to have been like this in the last couple of decades is Mr. Schumacher."

In the interest of remaining (relatively) impartial I won't add to that.

Massa's Ferrari is running an F-duct so it seems as though they will stick with it for quali. For those asking, an F-duct stalls the rear wing by increasing the flow of air to it. By doing that you reduce drag and increase the speed down the straight.

Looks like Rosberg's Mercedes also has a version of an F-duct on it, so Mercedes and Ferrari are catching up with McLaren in that regard.

To confirm, Alonso is also running an F-duct. On the Ferrari the inlet is on the shark fin engine cover on both sides.

Alonso still struggling with that car a bit, the rear end sliding wide in the final chicane.

Webber quickest with a 1:21.232, 0.467 up on Hamilton and 0.575 up on Vettel.

Massa also struggling with the Ferrari, the rear end coming round on him at turn 10.

Alonso and Massa are on soft tyres but not going particularly quickly.

Vettel is on hard tyres and is now second quickest, just 0.179 off Webber.

Ferrari says: "First run finished for both drivers. Both of them made a practice start."

"Has there been any news or signs of Alonso's left elbow hurting him like it seemed to be yesterday?" asks Dave.

I didn't notice that but I'll have a look if we get an on-board image.

Schumacher is out on the soft tyres, can he set a time to rival the Red Bulls and McLarens... He goes third fastest with a 1:21.583. That's a respectable time but Vettel was in the 1:19s yesterday on soft tyres.

Rosberg out on hards and therefore a long way off the pace of Schumacher.

Valvestech says: "Well I dont actually agree with Nigel but if he his right I think the Answer is 7 world title and 2 world titles."

Keep it clean chaps!

Stu: "Everyone can have a shot at the "Schu" now.. but where will your comments be when he is fully back?? I look forward to reading them sometime very soon. Doubt Schu at your peril.."

Tushar says: "I was wondering, Red Bull doesn't have an F-duct but still they are quicker than McLaren so why so much fuss about F-duct."

A good point, there is no replacement for a really sorted car like Red Bull's.

The F-duct is a new idea that can be added to a car and is very innovative, so it has captured everyone's imagination. It also helps overtaking a bit if the car behind has it and the other doesn't.

Ok, qualifying simulations starting now. Button goes fourth quickest with a 1:21.376, he was matching Webber in the first two sectors - he was on hard tyres though.

Sutil stops on track with a problem with his car, that's the end of his session - no obvious damage to the car. He lost power and the engine cut out.

Webber is on a fast lap now, but loses time in the second sector.

Vettel quickest on soft tyres with a 1:20.528. Webber heads into the pits, aborting a fast lap.

Rosberg winds up for a quick lap on soft tyres...

Webber is getting out of his car and that appears to be the end of his session. Maybe a problem with the car but his team was not expecting him to come in, he doesn't look happy.

Alonso 2 seconds off Vettel with his last lap on soft tyres.

"I just read that Virgin got a 5 grid penalty for the race! How come? " I think that was due to a gearbox problem, we'll look into it.

End of the session and Vettel is still way out in front. McLarens within a tenth of Webber who is 0.704 off Vettel.

Schumacher was a second off the pace in fifth, ahead of Massa, Rosberg and Alonso.

Thank you for joining us for practice. The all important qualifying session will start at 14.00 local time, make sure you don't miss it.