Murray withdraws from Toronto Masters with knee injury

Britain's Andy Murray pulled out of the Toronto Masters on Thursday with a left knee injury which he suffered only three days after winning gold in the Olympic Games men's singles and could cloud his US Open preparations.

Murray said the injury, which he suffered during the second set of his opening match on Wednesday, was due to a lack of time to prepare for the switch to hard courts from grass.

"I decided the best thing was to rest it and try and make sure I can let my body kind of adjust to the surface normally," Murray, who was scheduled to play Canada's Milos Raonic in a last 16 match later on Thursday, told reporters.

"The hard court is, for me, the hardest on my body and it always takes me a bit of time to getting used to playing on them again and I hope it doesn't affect the next few weeks."

Murray, whose triumph at the London Games was on grass, suffered the injury while chasing down a forehand and was grimacing on the court after repeatedly grabbing his knee.

He called a medical timeout while leading his match with Italy's Flavio Cipolla 6-1 3-2 and received about five minutes of treatment before returning to the court to finish.

Murray, who made the decision to withdraw after a warm-up on a bike earlier on Thursday, said his physiotherapist will be at next week's Cincinnati Masters where he will have more treatment and training before deciding how to proceed.

"The left knee, I've never really had many problems with it beforehand so that was another reason for making this decision. I want to make sure it's not something that I am going to play through and maybe damage a little bit more," said Murray.

"It's not ideal ... I wasn't able to do anything to adjust to the surface and get used to the movements at all so now I will be able to do that and give it a few days and see how it feels."

Murray's injury is the latest blow to a Toronto tournament that was already dealing with the absence of world number one Roger Federer and world number three Rafa Nadal.

The Toronto Masters in one of four lead-up events to the Aug. 27-Sept. 9 US Open, the year's final grand slam.