The Red Bull driver driver clocked a 1:14.442 to finish the morning ahead of Fernando Alonso and Friday pace setter Lewis Hamilton as glorious sunshine greeted the drivers at the Circuit Gilles Villeneuve and so the lap times tumbled after the drizzly and overcast conditions of Friday.
Mark Webber was fourth fastest ahead of Pastor Maldonado and Felipe Massa, but after his woes of yesterday that saw him manage only 12 laps in FP1 and just 18 minutes at the end of FP2 due to an oil leak, Jenson Button was off the pace again and could only manage the 15th quickest time.
After the heavy crashes of Bruno Senna and Heikki Kovalainen that brought out the red flags yesterday, there was further drama at the start of the session with Nico Rosberg parking up on the exit to turn seven after reporting a slipping clutch.
Rosberg has made it to Q3 in every session this season but his team will have to work hard now to get him there again.
Jean-Eric Vergne’s mechanics will also have their work cut out after he made a mistake into the first corner, touching the grass and planting his Toro Rosso straight into the tyre barrier, bringing out the yellow flags.
With most drivers switching to the grippier but faster-wearing super soft compound for the end of the session, Alonso jumped to the top of the times and it looked as if he would remain there but for Vettel’s late charge with three minutes remaining.
With less than three tenths between the top three, it looks set for a fascinating shoot out between the usual suspects but the Lotuses could be holding something back, Romain Grosjean and Kimi Raikkonen finishing just eighth and ninth fastest respectively.