Sebastian Vettel still extended his lead in the 2011 world championship despite losing the marathon Canadian grand prix on the very last lap.
"It's not the sweetest feeling," admitted the German, despite pulling out his lead - now over Button - from 58 to 60 points.
It was a marathon day at the Circuit Gilles Villeneuve, following an excruciatingly long red flag delay due to torrential rain.
Button's victory was epic, given his drive-through penalty, a high speed run from the back of the safety car pack, and collisions with teammate Lewis Hamilton and also Ferrari's Fernando Alonso.
I couldn't see anything and I've apologised to him
As for his clash with Lewis Hamilton, who had to retire, Briton Button said: "I couldn't see anything and I've apologised to him."
McLaren boss Martin Whitmarsh, meanwhile, is hoping the stewards will not issue a post-race penalty after Button tipped Alonso into retirement.
"I think Fernando shut (the door) on him," Whitmarsh said on BBC television, but Spaniard Alonso did not agree.