The Australian, on a two stop strategy compared to teammate and polesitter Nick Heidfeld's three stopper at the Nurburgring, qualified third but retired at the first bend.
"Williams has normally done well in Canada," said Webber, 28, who owned up after the clash with Juan Pablo Montoya.
The BMW-powered driver said Montreal, all straights and chicanes, is - aerodynamically - 'very different' to the high downforce Monaco and Nurburgring.
"And (it's) massive for the engine," said the 28-year-old.
"Hopefully we can be strong." -GMM