Ahead of today's sole free practice session, the air temperature is 23 degrees C while the track temperature is 28 degrees. It is bright and sunny.

Lewis Hamilton was quickest in both sessions yesterday, edging out Vettel and Rosberg in FP1 and the Ferrari duo in the second session. However, if things were going well for the 2008 champion it was a "Friday from hell" for his teammate Jenson Button who lost tracktime in both sessions.

Not for the first time, drivers found themselves caught out by the unforgiving barriers and walls here, Kovalainen damaging his Caterham in the morning and Bruno Senna coming to grief in the afternoon.

While Hamilton is looking good to become the seventh winner of the season, the Englishman feels his biggest threat comes from Ferrari. That said, the Mercedes duo is also looking good.

Tyre options are the same as in Monaco - soft and supersoft - with most predicting a two stop strategy on Sunday.

The lights go green and Kovalainen leads Kobayashi and Vergne on to the track. They are soon joined by numerous other including Raikkonen, Vettel, Massa and Schumacher, all but Pic and Glock on soft (prime).

Hamilton and Rosberg are the last to make an appearance however, the German grinds to a halt after Turns 8/9 on the approach to the hairpin. He tells of a "strange feeling" and the "clutch slipping". If they are unable to get his car back to the pits in time, Rosberg will miss the remainder of the session, a major blow to his weekend.

Ten minutes into the session, Kobayashi is the first driver out for a second run. He is joined, shortly after, by Button.

The Japanese crosses the line at 1:17.376, watched intently by Maldonado. Improving to 17.223, Kobayashi remains 1.785s quicker than Button who posts a 19.008. Back in the pitlane a number of drivers get ready to get back to work.

A 16.297 sees Button go quickest as Raikkonen posts a 17.150, the Englishman locking up into the hairpin.

"I'm really struggling," complains Button as he locks up again, Kobayashi re-taking the top spot with a 16.104.

Replay shows Karthikeyan taking a real pounding as he runs over the unforgiving Montreal kerbs.

It looks like an early bath for Vergne who goes into the tyre barriers at Turn 2. The car doesn't look badly damaged but the Frenchman climbs out of it. Replay shows the Toro Rosso driver lost it after running over the grass coming out of Turn 1.

The yellow flags are out as the Toro Rosso is pushed to safety, Button having re-taken the top spot with a 15.833. Kobayashi is second, ahead of Vettel, Raikkonen, Perez and Webber.

As Grosjean goes quickest in S1, Webber locks up going into the final chicane. Moments later Vettel posts 15.440 to go quickest.

A 15.566 sees Massa go second, Ferrari running its new (McLaren style) exhausts on both cars today.

Schumacher goes third (15.710) as Vettel raises the bar with a 15.022.

Alonso goes second with a 15.282 as the cameras pick up Schumacher really throwing his Mercedes around.

With 33:29 on the clock all but Vergne, di Resta and Rosberg have posted times. The Frenchman and German looking unlikely to do so.

Grosjean goes fifth with a 15.632, the Frenchman slotting in ahead of Maldonado, Senna, Button and Perez. Hamilton is currently twelfth, 1.239s off the pace.

Alonso crosses the line at 14.737 to go quickest but this is almost instantly beaten by Hamilton's 14.712 - the first drivers to break the 1:14s barriers this weekend.

Rosberg is now back in the Mercedes garage, sadly he doesn't have his car with him.

With 23:00 on the clock, Senna and Grosjean switch to options. Posting PBs in all three sectors, the Lotus driver crosses the line at 14.873 to go third.

Rosberg now eating a bowl of cereal in the Mercedes garage. Back on track, Webber goes fifth (15.307), the Australian still on the prime rubber.