Welcome back to our live coverage of the Monaco Grand Prix weekend. Over the next 90 minutes we'll find out who is going to be starting from the all-important pole position for this year's race. With overtaking so difficult on the tight and twisty street circuit, we can expect to see the top drivers pushing to the absolute limit to try and secure a place on the front row.

Alonso was fastest in final practice after leading the way on Thursday too. He's definitely in with a shot of taking pole position, but Red Bull will put up a much stiffer fight this afternoon than they did this morning. McLaren are also confident and neither of their drivers can be ruled out.

There were two big accidents in final practice. Rosberg slammed against the barriers heading down to the Nouvelle Chicane and Tonio Liuzzi crashed at Sainte Devote. Mercedes are working hard to get Rosberg out in Q1 but there is no work going on in the HRT garage, suggesting Liuzzi will not take part.

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Garrin says: "Any news on whether Rosberg will take part in qualifying? Saving his tyres perhaps not the worst result…"

The latest we know is that the team is working furiously on the car and will continue to do so until it is either ready or Q1 comes to an end. They obviously think there is a chance, so fingers crossed for Rosberg. Monaco is so tight, so there isn't the same advantage to be gained from saving tyres as you need to be able to pass on track to make that strategy work.

For Liuzzi the big question will be whether he is allowed to qualify for the race. It looks pretty certain that he won't set a time in Q1, which raises questions over the 107% rule. Our understanding will be that the stewards will look at his FP3 time of 1:20.115 and if that is within 107% of the fastest time in Q1 he will be allowed to start from the back of the grid.

Ex-F1 driver Alex Wurz has tweets: "Just spoke with some if my friends at Mercedes, Nico's car will be ready as it looks... Good."

Meanwhile Ferrari is well prepared: "Fifteen minutes to the start of the Q session at Monaco. Everything is ok in Scuderia Ferrari Marlboro garage."

The other big factor in this session will be traffic. In the GP2 qualifying session on Thursday cars were backing off in the final sector of the lap to try to get track position. That resulted in several accidents and quite a few penalties too.

The F1 drivers are more experienced and there are less of them, so it shouldn't be a problem but we have seen tempers fray in the past. And, of course, many will remember Schumacher's antics in 2006.

Force India is well aware of the problems of getting a clean lap around here: "This is probably going to be the most crowded qualy session of the year, and arguably the most important. Good luck guys."

Virgin is making its final adjustments to its cars: "Final tape going onto the engine cover. As soon as we leave the pitlane we can only adjust front wing and tyres"

Alonso is in his car and ready for the start of the session. Rosberg has his helmet on but is stood at the back of the Mercedes garage.

The session gets underway with d'Ambrosio the first man to leave the pit lane.

Schumacher and Petrov have joined the Virgin in the hope of getting a clean banker lap.

The Renaults are out on softs, which is the prime or harder tyre here. For many teams the big question will be whether they can make it through Q1 without using the super-softs, saving for the race or later in the session.

Petrov clocks a 1:18.112, d'Ambrosio is about five seconds off that in the Virgin on his first timed lap.

Rosberg will get out in this session after a brilliant job by his mechanics.

Ferrari says: "Everything is ready inside the garage. We're just waiting for the right time to run. Here traffic is a decisive factor"

Button is out on track and goes fastest with a 1:17.059. vHamilton is also out there and is going about 0.6 seconds quicker.

But they are all on the soft tyres which offer up several fast laps.

Hamilton sets a 1:16.321 to straight to the top of timing screens.

The McLarens continue to trade fastest laps as Button goes to the top once more with a 1:15.969.

Vettel, Alonso and Massa are all on track now.

Vettel sets the second fastest time at his first attempt - roughly 0.4 off Button. But the times are improving with every lap on these soft tyres up until about the fourth or fifth flying lap.

Vettel goes top on a 1:15.606 and was immediately beaten by Button.

Alonso is currently fourth fastest.

Rosberg is out on track now.

Meanwhile, Karthikeyan is stood at the back of the garage without his helmet on. That suggests both HRTs might sit out of this session.

Rosberg immediately pops into the top five, showing no signs of fear on his first lap since his practice crash.

Buemi is out on super-soft tyres to try and ensure he's not going out in Q1.

At the moment it looks as though the HRTs and Virgins will be going out in this session. They will likely be joined by the Lotuses, although Trulli is currently 15th.

Schumacher has also gone out on the super-softs, so even he doesn't feel safe.

Alguersuari has gone into the back of one of the Saubers at La Rascasse. An example of how crowded it can become in that section of track. Very minor damage to both cars.

Schumacher only gets up to sixth with the extra grip of the super-softs. Not a great result on those tyres considering the other frontrunners have set their times on softs.

Alguersuari is in the pits after his collision and looks as though he will drop out with the Virgins, Lotuses and HRTs.

A good effort by Trulli to get within 0.3 seconds of Kobayashi and he should get one more run.

Kobayashi improves on super-soft tyres.

Kovalainen also improves but still isn't quite close enough to the midfield to worry the likes of di Resta and Heidfeld.

Neither HRT took part in that session but both drivers were within 107% of the Q1 time in FP3. based on previous races when Kobayashi and Heidfeld failed to set a time, that means they should be allowed to start the race.

It's also worth mentioning that the two McLaren finished that session first and second ahead of Vettel. Maldonado, who has been very quick here in the past in GP2, was fourth fastest on super-soft tyres.

HRT say: "We found a problem in the rear suspenssion of Narain's car at the end of P3 and we couldn't fix it for qualifying"

Buemi and Sutil lead charge to the track at the start of Q2. They are joined by the two Mercedes, which both used a set of super-softs in that last session.

Force India says: "Squeezing through to Q3 will be tough, but we'll give it our best. Grid position is more important here than anywhere."

Buemi clocks a 1:16.735 on the super-soft tyres, while his team-mate Alguersuari, who got knocked out in Q1, has been summoned by the stewards.

Hamilton has now gone quickest with a 1:14.275.

Heidfeld is struggling with the wrong type of bounce. Renault says: "Nick reports too much bounce in turn 5, and not the right type of bounce." I'm not sure what the right type of bounce is.

Hamilton is back in the pits with a 1:14.275 to his name. Button is on a quick lap though.

Button is third fastest with that last lap despite going quickest in sector one. Vettel is currently splitting the McLarens and is less than a tenth off Hamilton.

Vettel hooks up another quick lap on his super-softs and is just 0.002 off Hamilton this time around.

Massa has had to take to the run off a couple of times in the second part of the swimming pool section.

Williams is looking much quicker than in recent weeks, with both its cars currently in the top 10. Renault looks quite a bit off the pace around here.

Massa gets into the top five on the super softs.

Perez hooks up a great lap to go eighth fastest.

Schumacher, Maldonado and Barrichello are fighting over tenth at the moment. Kobayashi will also want to get in on the top ten action.

Petrov is trying to sneak through in this session and is currently 11th.

Petrov is out as he returns to the pits, his team-mate Heidfled looks as though he is going to join him.

Barrichello can't improve on 12th so he is out.

Schumacher, Perez and Maldonado go through in eigth, ninth and tenth. That's the second week in a row that Maldonado has made the top 10.

Perez won the GP2 feature race here last year and Maldonado won it the year before, so both have a proven record here and are living up to their reputations.

Ferrari gives an update on the tyre situation at the top three teams: "Now there are two sets of options available for Red Bull, McLaren and Ferrari drivers"

So, this is one of the most important qualifying sessions of the year. Schumacher has gone out first and is joined by the two Ferraris.

Button and Webber have also gone out but Vettel and Hamilton are leaving it a bit later.

Schumacher sets a 1:15.020 on his first attempt.

Alonso is about three seconds off on his lap so clearly had some kind of problme around the lap.

Button clocks the fastest lap of the weekend with a 1:13.997. Great lap and Webber can't match it.

Hamilton still hasn't left the pits as Vettel is on a very quick lap.

Vettel takes provisional pole with a brilliant lap. 1:13.556, 0.4 seconds up on Button.

Hamilton is now leaving the pits and will get one good shot at this on fresh tyres.

Button is out with another set of brand new super-softs on his car.

Hamilton would have lost a lot of time through Massanet as he came up behind Massa's Ferrari. It was a very poor first sector as a result.

Perez has crashed heavily at the Nouvelle Chicane. That was the same place Rosberg crashed this morning but this time the car is in the barrier separating the track and the run off zone. It would have been a very heavy impact and he took it sideways judging by the car's finishing position.

The ambulance is at the scene and we still haven't seen him get out of the car.

A replay shows that he got a little wide coming out of the tunnel and then lost control over the crest heading towards the braking zone for the Nouvelle Chicane. He clipped the barriers on the right which pitched the car into a quarter spin and ended up hitting the barriers sideways.

The first impact was pretty big and tore the front tyre from the wheel. But the second impact was the worst.

Marshals and doctors are at the scene tending to Perez. They will be making sure they take every precaution to get him out of the car as safely as possible and avoid making any injuries worse.

The other drivers are still sat in their cars waiting to see what will happen next.

Perez appears to be out of the car now and in the ambulance.

The side of the car has been utterly demolished but the safety cell looks as though it is in one piece.

The latest is news from the pit lane is that Perez is conscious and making his way to the medical centre now for further checks. He was also talking to the doctors at the scene.

2:26 remains on the clock. So the drivers should have a chance to complete another lap if they want to. Hamilton and Maldonado have yet to set a time so presumably they will go out again.

Ferrari says: "All our thoughts are for Sergio, a Ferrari Driver Academy driver. Let's hope he is in good conditions" Adding: "Now they have to rebuild the barriers, something which will take some time."

Vettel is currently quickest on a 1:13.556 - a pretty tough time for anyone to beat with one flying lap.

The Tecpro barrier is being manipulated back into shape. Race director Charlie Whiting is down there to oversee the rebuild.

Mercedes says: "Q3 should restart in 5min"

So the drivers will have to clear their minds of what just happened and go out and try to set the fastest possible time.

To clarify Mercedes' comments, Q3 will restart once the barriers are safe again and the teams will be given 5 minutes notice.

We've now heard that the session will restart at 15:35 local time. So that's about seven minutes time.

Finding a gap in the traffic will be tough in this final two minutes. All the top drivers have been shown in their cockpits on TV during the break suggesting they intend to go out again.

Hamilton and Button are at the front of the queue for the restart with over a minute to go. They will be losing tyre temperature and gaining huge amounts of engine temperature.

Alonso heads down the pit lane too. One of the Mercedes is also in the queue.

We're back underway. Button, Hamilton, Rosberg and Alonso are out there.

All nine cars are now out for one final run.

Hamilton has got a clear track ahead of him but will have just one flying lap.

Hamilton starts his lap and looks like he is struggling with tyre temperature in the first sector. He's 0.3 seconds down in the first sector.

Button aborts his lap at the Nouvelle Chicane.

Hamilton can only manage seventh fastest. Rosberg is back in eighth. Vettel, Button, Webber and Alonso did not improve on their laps.

So McLaren's decision to send their cars to the front of the queue appears to have backfired. Hamilton struggled with grip throughout the lap and he ended up roughly 1.7 seconds off the pace.

The celebrations are fairly subdued following Perez's accident.

But it is Vettel's first pole position at Monaco and puts him as the clear favourite for tomorrow's race. McLaren may have got closer without the stoppage for the accident, but choosing when to run in qualifying is all part of teh strategy.

Thank you for joining us for today's coverage. Make sure you keep checking the website throughout the afternoon for updates on Perez's condition and all the reaction from the teams and drivers to the session.