Ralf and Button get flying start

Ralf Schumacher and Jenson Button both made a clean start to the Canadian Grand Prix from their front row positions, but there was trouble for David Coulthard and Jarno Trulli.

The German Williams-BMW driver led Button in his BAR by 1.1 seconds after the first lap as the notorious first corner at the Circuit Gilles Villeneuve catered for just the one incident involving Coulthard.

Renault star Trulli remarkably pulled off track within 100 yards of the start and was immediately out of the race due to an apparent problem with the car.

But as the leaders made it through the first two tricky corners, Coulthard became embroiled in a midfield battle and spun in his McLaren, causing confusion towards the back of the pack.

Button’s BAR team-mate, Takuma Sato, who was provisionally 17th in qualifying after a spin late in his lap, chose to start from the pit lane to avoid possible tail-end trouble from the off.

Coulthard's spin led to Christian Klien bouncing into the air and onto Jaguar team-mate Mark Webber, who was forced to pit due to a puncture, relegating the Australian to the rear of the field before he retired at the end of lap eight.

In what was clearly a tight and entertaining start to the grand prix, the leading seven drivers were separated by just 10.5seconds after the opening 10 laps.

Ralf Schumacher was holding off Button by 3.5secs, with the Briton closely followed by Fernando Alonso in the second Renault.

Juan Pablo Montoya, in the other Williams-BMW, had Michael Schumacher on his tail in the leading Ferrari, with team-mate Rubens Barrichello in sixth after he had passed Kimi Raikkonen on lap seven.

Coulthard was the first to pit at the end of lap 11, followed a lap later by Raikkonen, with the crew turning the Finn round in 7.8 seconds.

Button was next in, and out in seven seconds, while Montoya pitted at the same time and was 1.5 seconds slower, with Ralf Schumacher taking a further two laps for his stop and 7.3 seconds.

Crucially for the 28-year-old he emerged ahead of Button, leaving Alonso at the head of the field for a lap before he followed the lead of the others, however, the Spaniard took on board a considerable amount of fuel as his stop took 17 seconds.

Barrichello was next in, followed by Michael Schumacher, with their stops taking 8.9 and 10.3 seconds respectively.

By the end of lap 20, Ralf Schumacher’s lead to Button was four seconds, with Michael Schumacher up to third, followed by Montoya, Barrichello and Alonso.

Raikkonen's hopes of a high finish were hit by a drive-through time penalty for crossing the white line at the pit exit, an elementary mistake for an experienced driver.

There was drama, though, at the end of lap 21 when Nick Heidfeld came in for his stop, pulling away too quickly after receiving fresh tyres and more fuel, knocking over one of his own pit crew who required treatment.

Up front, Button was taking a couple of tenths of a second off Ralf Schumacher as each lap passed, to such an extent that by lap 30 the gap was down to just 3.2 seconds, although backmarker Timo Glock, in his debut drive for Jordan, had held up the Briton at one point.

Behind them, Michael Schumacher and Montoya were enjoying their own duel for third, and was right on the tail of his great rival until he pitted for a second time on lap 30.