Despite making no fewer than six pitstops, Jenson Button secured his first win of the 2011 F1 season in a frankly astonishing Canadian Grand Prix after defending champion Sebastian Vettel threw away victory with a mistake on the final lap of the race.
Poor weather conditions led to a start behind the Safety Car, a stoppage of more than two hours and multiple caution periods before a dramatic dash to the flag that ended with Vettel buckling under Button's pressure just a handful of corners from the chequered flag.
Vettel had led the field away behind the Safety Car at the start of the race after persistent rain in Montreal and set about building a lead ahead of Ferrari pair Fernando Alonso and Felipe Massa when the field was released at the start of the fifth lap.
Behind, Mark Webber's hopes of victory took a hit when he was tipped into a spin by Lewis Hamilton into turn one and dropped down the order, while Hamilton lost position to both Nico Rosberg and Michael Schumacher having been delayed himself.
As Vettel set about trying to pull away at the front, Hamilton was trying to fight his way back up the order but lost a further place to team-mate Button on the sixth lap when Schumacher ran him wide at the hairpin as the McLaren tried to come round the outside.
The move would be the catalyst for the main talking point of the early stages as Hamilton then tried to reclaim position from Button when the 2009 title winner got slightly out of shape exiting the final corner, with Hamilton putting his nose alongside Button only for the pair to touch on the pit straight. While Button escaped, Hamilton made contact with the pit wall which damaged the left rear of his car and forced the Briton out – with the Safety Car deployed to clear the debris from the circuit and allow Hamilton's car to be retrieved after he ground to a halt at turn five.
Under the Safety Car, Button – who came on the radio to ask the McLaren team what his team-mate had been doing – pitted for intermediate tyres with Vettel leading the race from Alonso, Massa, Rosberg and Schumacher.
When the race resumed on lap 13, Vettel got a good enough restart to put distance between himself and the Ferrari's behind. However, all eyes were on Button to see how quickly he would now lap and, despite losing more places with a drive-through for speeding under the Safety Car, he was soon noticeably quicker than the cars ahead.
Alonso, Rosberg and Schumacher all pitted for intermediate tyres only for a torrential downpour to put the Safety Car back on track, with Vettel and Webber both pitting for a new set of wet tyres with what was basically a free stop. Those cars to have changed to intermediates were also forced back into the pits with Vettel running in the lead behind the Safety Car from Kamui Kobayashi, Felipe Massa, Nick Heidfeld, Vitaly Petrov and Paul di Resta – the order having been shuffled as some drivers elected to stay on track on their original wet tyres.