“I’ve been struggling with my shoulder for a couple of weeks now, pretty much since the start of the hardcourt season two weeks ago.

“I think maybe the change of surface and balls since coming from the Olympics was just too much, and I’ve played a lot this year as well.

“I’m going to go and have some rest now and hopefully be ready for (the US Open).”

- top seed Agnieszka Radwanska after pulling out of the tournament with a right shoulder injury