Welcome back to Monaco for the second practice session of the weekend.

Fernando Alonso was the pacesetter this morning, just edging Sebastian Vettel by the narrowest of margins. This afternoon's session should give a clearer image of who's fastest as drivers attempt soft tyre runs and the track conditions improve.

Three Renault-powered cars were in the top four with Kubica, Vettel and Webber all challenging Alonso.

The sun is still out and the air temp is up to 21C. However, there are dark clouds looming on the horizon and they could bring rain about an hour into this session.

An update from Lotus: "Showers around behind the mountains but no rain expected for the start of the session"

The session has started but just Senna and Glock are out on track.

HRT's lap times from FP1 were slower than the times from GP2 qualifying, just shows how much they are struggling.

Hamilton and Webber are out on track, Lewis about to set the fastest time.

Kovalainen jumps out his way in the Lotus and he sets a time of 1:20.193.

Hamilton gets blocked by Chandhok into St Devote, as Glock runs wide at the same corner and has to spin around and rejoin.

A question from Stuart: "Why do drivers do one lap at the beginning of each practice and then come straight into the pits?"

The drivers are just checking that everything is working properly and the telemetry is feeding back to the pits. It's like a systems check for an F1 car.

Hamilton sets a 1:17.709 to go 0.045 faster than Sutil.

Bruno Senna locks up under braking for the Loews hairpin and just avoids the barriers. He manages to keep it going though.

Liuzzi is now fastest with a 1:17.537. A lot of the teams are saying they will focus on race pace in this session so we might not see the headline times we'll get on Saturday.

The two Red Bulls and Kubica now top the times, as the goalposts shift constantly early in this session.

A question from Robert: "Hi guys! Just wondering why Lewis Hamilton was credited with a finishing position last week, placed above other drivers who were still running, even though he crashed out of the race?"

He completed more laps than the slower cars that, although they passed the chequered flag, were three or four laps down.

Schumacher sets the second fastest time but it's Kubica who goes fastest now. He was absolutely on the limit again, a very impressive display of driving through the final corner.

Webber now fastest with a 1:16.056, 0.045 up on Kubica.

Adrian Sutil comes in from third fastest. "Tyres still need some time to come in but general balance is good, no real complaints."

Tonio Liuzzi back in: "Bit better than before, car is more driveable. Losing a little in turn 5 & 6 but getting better."

Kubica gets his Renault incredibly sideways to set a time of 1:15.589 - very impressive.

Alonso steps the rear end out into the Nouvelle chicane, it looks more like a rally car than an F1 car. He's third fastest with a 1:16.186 as the clouds come over.

To put these times into perspective, the fastest time from last year's qualifying was 1:14.514, set by Kimi Raikkonen. A similar lap time should be possible on Saturday for the fastest drivers.

Webber is now back on track, lapping 0.5 off the Renault's pace. Button puts in a time two seconds shy of Kubica but is probably on a heavy fuel load.

Rain predicted in the next half an hour or so.

Mercedes confirms the bad weather could be coming in: "Jock Clear's telling Nico that the weather is closing in... there's a big grey cloud over the mountain now."

Webber is now within 0.155 of Kubica.

Di Grassi wants changes to his suspension ahead of his next run: "Lucas wants to make a couple of changes to help traction over bumps," says Virgin. The team adds: "Planning track position is a bit tricky. But we can see where all the cars are on the track so the drivers know how many cars to let past"

Webber gets within 0.031 of kubica on that last lap but is losing time in the first sector.

Vettel's car looks far more controllable than in the first session but he is still 0.476 off Kubica.

Buemi comes across an HRT on a hot lap but easily gets past him. Buemi is on soft tyres so this could be a good lap. He's eighth fastest.

Massa, also on soft tyres, goes fastest and is immediately pipped by Alonso on softs. Maybe the teams are trying to get some data ahead of the predicted rain.

Alonso slams in an 1:14.904, he's the first to break into the 1:14s.

Gert asks: "You mention most of the teams will focus on race pace during this session. Why would they spend a whole session on this? I would get the car perfect for quali and do some estimated setup work for Sunday to ensure optimum starting position. A slow driver can defend with a good pit stop strategy at Monaco, but a very fast driver cannot pass…"

It's more about understanding the tyres, how long they will last and when they will have to pit - you cna lose a lot of positions with a botched strategy. Remember the set-up is the same for the race and qualifying due to Parc Ferme rules, so the work they are doing now will contribute to qualifying. Also the track will be different on Saturday so it makes more sense to prepare for qualifying during FP3.

Hamilton just nudged the barrier out of the final corner. He looks a bit sheepish starting his next lap but no obvious damage.

Rosberg returns to the pits after setting the second fastest time using soft tyres.

Johannes says: "17 years ago the name Senna was at the opposite side of the timesheet , quite sad . HRT cars are really too slow.."

Webber is now running on soft tyres but is almost certainly on heavy fuel, preparing for the start of the race.

Lotus report a problem with Trulli's car: "Jarno has to stop with an engine problem"

"What is Schumacher doing differently from the earlier 4 races since he seems to be faster the Nico Rosberg now? Is it the difference in the weight distribution as mentioned in the Spanish GP? Surely this cant make such a big difference from being a couple tenths down to a couple of tenths up, that equates to almost half a second which is a massive improvement in F1 as we all know."

Schumacher had a damaged chassis in three of the first four races and that has probably been a little overlooked. He was also really struggling with understeer and he has cured that problem. It's all about getting used to driving an F1 car again. I don't think it is that surprising that after finding improvements for the car that directly effect his confidence behind the wheel, he had found a significant amount of time. Also, Rosberg hasn't adapted as well to the new car.

Rain is forecast in the next five minutes by Mercedes. A lot of the big names are out on track but nobody is setting personal bests at the moment.

Big mistake for Alguersuari that kicked the rear end out under braking for the Nouvelle chicane. It was a tank slapper reminiscent of Kimi Raikkonen's in the race in 2008 when he took out Sutil. He did very well to hold onto it but completely missed the chicane. Fortunately there was no Force India for him to smash into.

A light sprinkling of rain sees quite a few cars return to the pits.

Alonso is staying out and is still clobbering the kerbs.

Hamilton puts in a reasonable time, 0.6 off the best and with a flat-spotted front left tyre.

Roger says: "Actually, Rosberg is faster than Schuey. And note, they are not using the new long-wheelsbase configuration at Monaco, so it's back to where they were for the first 4 races."

That's true of Monaco, I was referring to Spain in the comparison. It's still a bit too early to say who has the upperhand this weekend.

di Grassi has a big lock up into Sainte Devote, manages to come out undamaged.

Kovalainen gets past a very slow Massa who appeared to be slowing up in order to get a quick lap. Now he will have to sit behind him for a lap. And on the next lap Massa holds up Glock while trying to find some space.

Mark says: "In regards to Michael's turnaround, if the chassis is damaged that was a BIG issue. But something that is often overlooked with drivers, is the fact that you cannot change the way a successful driver, drives the car. You have to make the car work for the driver not the other way around. Drivers can only change their driving style just so much. You absolutely need the driver to work with the car in a perfectly natural manner, if you can't give a driver that feel, he will be less than his best."

Talking of Schumacher, he had to skip the Nouvelle chicane after a mistake just then. Track conditions are far from ideal now.

Kubica is still absolutely on the limit as more rain falls on the track. He's been great to watch all day and should challenge the big teams in qualifying this weekend.

The currsnt lap times are a long way off the best we have seen today as drivers focus on long runs on the soft tyres - Vettel was 3.5 seconds off the pace on that last lap.

There was nearly a collision between Schumacher and Button in the pits as the Mercedes came in and the McLaren went out. This pit is so tight in Monaco that accidents can and, very easily do, happen.

Even more drops of rain are falling as we enter the last nine minutes of the session.

Massa loses the rear end under braking on the damp track at Sainte Devote.

Mark asks: "I have been surprised with Massa, he had been fast for a number of years. This year he has not shown any of that speed. Any ideas? Do you suppose that the accident last year has hurt him in more than anyone has let on?"

Possibly but I couldn't say for certain. He claims to have no problems on that side and Ferrari say it is more down to set-up problems with the F10 than a lack of raw pace. He is also being compared to Alonso now, who seems very happy with the way this year's Ferrari handles.

Five minutes left and we are still seeing laps about two or three seconds off the pace of Alonso's best time of 1:14.904.

The track is still dry but there is dampness in the air and it has had a slght impact on grip levels.

Nishan: "Let's assume that there is a dry qualifying session and it rains on race day. How would it impact on the preparation of the cars for the race setup? What changes are allowed on the cars on race day?"

They are allowed to change tyres and then they can make adjustments to the car in pit stops such as the front wing (and if you're Ferrari, ride height as well). Basically if rain is predicted on Sunday the teams have to gamble on set-up on Saturday.

Just seconds remaining and no-one is on a fast lap.

Alonso going very slow waiting for a gap in the traffic, his lap won't count because he crosses the line after the chequered flag but he will still get a bit of data for his team.

So Alonso will hold onto his position at the top of the timesheets. For the second session in a row he is the fastest man, with Rosberg 0.109 slower and Vettel 0.195 adrift.

Thank you for joining us today. Tomorrow we get a day of rest before the F1 cars return to the track for Saturday practice. Make sure you keep checking back to ESPNF1 for all the latest news from the Principality.