Welcome back to ESPNF1's commentary of Friday practice from the Canadian Grand Prix. It was a strange first session with Nico Rosberg finishing top of the pile and Sebastian Vettel finishing his session in the 'Wall of Champions'. But that's why we love the Circuit Gilles Villeneuve and we should be set for even more surprises over the next two days.

But first things first, we've got another 90 minutes of practice today in which we should see more representative lap times from the frontrunners on the super-soft tyres.

© Sutton Images

There are reports that de la Rosa is stepping in for Perez for the rest of the event at Sauber. We'll bring you confirmation as soon as we can. Of course, Perez had a huge accident at Monaco two weeks ago, but he passed a medical to take part in practice this morning.

The BBC has confirmed that de la Rosa will be standing in for Perez, starting in this session. Clearly Perez isn't 100% happy with how he felt in FP1.

Meanwhile, the top drivers are preparing for their sessions. It will be a crucial 90 minutes to get the car sorted in time for qualifying tomorrow.

The session gets underway with Alguersuari making his way out on track and scaring a flock of birds off the circuit at turn three. We've also heard this weekend that all the marmots that live on the island have been hearded up and removed for their own safety. Although that story has not been confirmed!

Kovalainen is the first man to make a mistake at turn one and skipped the chicane.

Christian Horner has confirmed that Vettel's car is ready for this session after both crews worked on the car after FP1. There was no major damage to the chassis.

Di Resta has got striaght down to work with a 1:20.038 but we should see laps over five seconds faster than that by the end of the session.

Apparently Perez was feeling sick after FP1 so decided not to risk taking part in the rest of the weekend. A very mature decision from the 21-year-old Mexican.

Most the drivers appear to be out on the medium tyres which won't actually be used over the rest of the weekend. Pirelli has given each driver two sets to test today on top of the two sets of softs and one set of super-softs they usually get. The mediums will make their race debut at the next grand prix in Valencia.

Heidfeld has now gone fastest with a 1:17.037, Webber is 0.2 tenths slower in second.

Felipe Massa told to cool his brakes on entry to the corners, clearly Ferrari are running close to the margins with their brake ducts this weekend.

Vettel goes fastest on soft tyres with a 1:16.262. He's immediately back on the pace after his morning accident.

We can also confirm that Vettel's KERS is working this weekend - at the moment at least - although he didn't use all of it on his last lap, which was a 1:15.739.

Massa holds a healthy slide through the final chicane, he's looked quite ragged so far today so could still be struggling with the balance problems he's had so far this season.

Sergio Perez said: "Of course I wanted to drive and I had no doubt I was alright. But apparently this is unfortunately not the case. I am deeply disappointed. I spoke to the team after the session and told them that I'm not a hundred per cent fit. I only want to drive when I'm a hundred per cent well. I need some more time to recover."

Peter Sauber added: "We want to thank Pedro de la Rosa and McLaren for helping us out in this situation." De la Rosa is a McLaren test driver. Sauber's third driver, Esteban Gutierrez, is in his native Mexico this weekend.

Vettel has improved to a 1:15.467 but is now back in the pits. Hamilton is second (also in the pits) 0.501 seconds off the Red Bull. Button (on track) is third fastest 0.012 slower than his team-mate.

If you want to ask any questions during the session or have your say on anything F1 related then get in touch by clicking on the link above this window.

Ruston asks: "Where do you think Force India's drivers could land in the time sheet? And do you think Nick Hiefield could get a seat with Force India next year?"

This should be one of Force India's stronger tracks so I would not be surprised to see one of the cars in the points on Sunday. The car has good straight-line speed, which bodes well for a quick lap.

As for Nick Heidfeld, I haven't heard anything to back that up. Nico Hulkenberg is next in line for a drive at Force India and wouldn't be surprised at all to see him step up to the team should Sutil or di Resta move on.

Phil says: "Why is Esteban Gutierrez in Mexico? You would think a third driver would not want to miss the next race after a a regular driver's big crash..."

A very good question and not one I have the answer to. In Sauber's defence Perez passed a medical in Monaco after the crash, in Zurich mid-week and in Canada on Thursday. Peter Sauber said: "Nobody could have foreseen that he would feel unwell. Maybe we are being overly cautious, but when it's about the health of our drivers we take zero risks."

Vettel is still on top and still in the pits. His Red Bull team-mate Webber is back on track but lapping well off the pace.

Hamilton is heading back on track.

In reference to the plans to bring in 1.6 litre turbo engines to the sport in 2013, Carlo says: "It is a shame the pinnacle of motorsports is will be using lawn mower engines in 2013. Next they will be asked to drive around with parachutes behind the cars."

Sean asks: "What's the rule with the two DRS zones this weekend? Are there two detection points? because there should be! We want to see battles, not just plain overtakes "

Sadly there is only one detection zone. So if a driver gets past in the first zone then they will be able to use their DRS again in the second zone to pull away and the car that has been overtaken will not be able to battle back.

Massa and Alonso are now second and third, with Massa just 0.125 seconds off Vettel.

Hamilton was on a very quick lap but missed the final chicane and had to abort his lap.

De la Rosa is getting ready to head out for the first time but will be wearing McLaren overalls, which is slightly odd.

Vettel is back out on soft tyres but is lapping quite a long way off the pace in the second and third sectors.

Charlie asks: "Why is the Ferrari so off pace. Reports really don't point to any one thing. Is it the backend of the car for down force, or front end not hooking up in corners? What new parts do they bring to Canada?"

Ferrari simply doesn't have enough downforce on the car this year. On the hard tyres that also created tyre warm-up problems, but the car is quicker on the softer tyres used here. This weekend they have some minor upgrades to the diffuser and rear wing but are planning a more comprehensive upgrade for the British Grand Prix.

Having said all that, Alonso has now gone fastest with a 1:15.205.

Vettel just set the fastest middle sector yet but is still slower than Alonso's Ferrari. We're still waiting to see the first super-soft tyre hot lap from one of the front runners. Petrov is currently using them and sets the 10th fastest time.

The top eight drivers are back in the pits.

Zhi Chang Joo Hu asks: "Why dont the FIA just establish a certain fuel consumption for the engine, and let the makers do whatever engine they want to?"

There will be a fuel restriction in 2013 but the engine layout will be restricted to 1.6 litre, four-cylinder turbos. The FIA are also trying to limit costs as much as possible so an open rule book would be expensive, in fact some teams are arguing that we should stick with the V8s to keep costs down.

Petrov has improved to seventh on the super-soft tyres. The top six are still in the garage but they should be coming out pretty soon.

Sutil ran wide at seventh and has broken his front-left suspension. He's stopped on track and his session is over.

Grant says: "1.6 liter turbo lawnmower? Some lawnmower. If you want to be a purist... real F1 engines have 16 cylinders... although 12 is OK if the car is red... "

I assume you're referring to the BRM V16 Grant? It was a magnificent attempt at over-engineering!

Sutil is fine and his car has been wheeled away without the need of a red flag.

Massa and Hamilton are back on track, as is Webber.

Matt says: "Why go with 4 cyl? 6 would be interesting. Nissan gets 500 HP out of the GTR engine with 20 MPG on the highway. Certainly it could meet both HP and Conservation parameters. What is magic about the 4 cylinder. Or a bigger one. Offenhauser 4 cylinders certainly made great sounds in there day!"

Kobayashi has hit the barrier at turn four. The car looks pretty mangled. He took too much kerb in turn four and the car skipped into the barriers. Kobayashi is being taken away by the FIA doctor but looks OK.

Both the front and rear right suspension is pretty badly damaged.

Meanwhile, de la Rosa now looks like he is ready to complete his first lap of the day. It would have taken a long time to get him comfortable in that car as he is quite a bit taller than Perez.

Miran from Slovenia asks: "I need objective explanation why would anyone wish Michael Schumacher on his team? No good driver, no good results, no good for team image, no good for sponsors... It would be cheaper for Mercedes to choose someone else (Sutil, for example)."

A contentious point, but I would argue Schumacher is very good from a marketing point of view as he still has a lot of very loyal fans. It's true that he hasn't been as quick on the track as he always used to be, but Rosberg has been driving very well as his team-mate and the Mercedes is particularly hard on its tyres, which means he has been struggling in the race compared to the cars around him.

The session will restart in 90 seconds time.

Kobus says: "A few years ago they had v6 turbos. Ferrari is more inclined to go for a v6 than a four. Surely they can engineer a 1.6 v6?"

Carlo says: "Didn't they use 1.5 liter Turbos in the 80's? I remember they used to blow up quite nicely. Don't see many of today's engines expiring. There is a much greater engineering challenge producing horsepower in a normally aspirated engine."

There was a four-cylinder 1.5 litre BMW engine that used to power the Brabhams run by Bernie Ecclestone.

We're back underway and de la Rosa is out on track immediately.

D'Ambrosio has gone into the wall at turn three in what looks like a very similar accident to Kobayahsi's.

Another red flag. D' Ambrosio actually lost the car earlier on the entrance to turn four and hit the same kerb Kobayashi did, which launched him into the wall. He also hit the wall a little more straight-on.

Hamilton has picked up a puncture on his super-soft tyres so won't get a quick lap in today. He has got back into the pits but the right rear tyre is absolutely ruined.

14 minutes remaining and the session is back underway. A train of cars leaves the pits and you can see how dusty the trackis as clouds of dirt are thrown up.

Alonso, Vettel and Massa are back on track. Hamilton has gone back out on a new set of tyres.

Button and Webber are also out.

Ferrari says: "Both drivers are out with the super-softs"

Vettel has got a lot of cars in front of him and is told to overtake Heidfeld and Alonso to try and get a lap in.

Alonso sets a new fastest first sector.

De la Rosa has set a lap but is second slowest. It's going to be hard to get on the pace in such a short amount of time.

Hamilton has gone out on soft tyres so won't be setting an impressive time in this session.

Alonso is still fastest with a 1:15.107, 0.369 up on Vettel.

After setting the fastest time in FP1, Rosberg is just 18th fastest in this session. Mercedes said they were going to work on their tyre degradation issues today so are clearly running heavier fuel loads.

The session is coming to a close and it doesn't look as though anybody will beat Alonso.

It was a bit of a mixed session and you get the feeling we still haven't seen the best from McLaren and Red Bull. The Ferraris are definitely competitive here, so it should make for a brilliant qualifying session and race.

Make sure you don't miss any of the action by joining us tomorrow for qualifying and on Sunday for the race. In the meantime, keep checking the website for all the latest news and reaction from the drivers and teams.