Andy Murray withdrew from the Rogers Cup because of a knee injury Thursday, the latest top player to pull out of the rain-delayed tournament.
The Olympic gold medalist hurt his left knee Wednesday night during the opening match against Flavio Cipolla. Murray was scheduled to face Canadian Milos Raonic in the third round Thursday night in the event where all singles play was wiped out by rain.
"Normally when I move on to hard courts, I have 10 days or so practicing and you feel things like this, but you can work around it by doing the right training and what not," Murray said. "I don't want to go full out and possibly do any more damage. That was why I decided not to play."
Murray, ranked fourth in the world, said he's unsure whether he can play in Cincinnati next week or what his status is for the U.S. Open.
"Over the next few days we'll come up with a plan and strategy to either get myself ready for Cincinnati, or if not, then plan for the best way to prepare for the U.S. Open," Murray said. "But today I won't think about any strategies or whatever. It'll just be about what's the next move and where do we go from here."
Roger Federer and Rafael Nadal withdrew before the tournament began.
Raonic reached the quarterfinals for the first time in a Masters tournament.
"Obviously, it's something that I was really looking forward to," Raonic about playing Murray. "It's an unpleasant thing, but at the same time it's a good thing -- it's my first quarterfinal in a Masters and to be at home is pretty special. I guess there's a give and take with it. I'm playing pretty well, I'm healthy, so it's a good opportunity and I'm going to make the most of it come tomorrow."
Top-seeded Novak Djokovic will face Sam Querrey on Friday in one of the postponed matches.