Andy Murray withdrew from the Swiss Indoors yesterday shortly before his match with Dutchman Robin Haase with a right buttock muscle strain. The World No 3 was replaced in the draw by Swiss Marco Chiudinelli.
The pullout came after Murray, winner of three titles last month in Asia, had requested a wild card into the event featuring rivals Novak Djokovic and Roger Federer.
Murray said that he woke up around 3 am on Tuesday with the pain in his buttock.
"I was struggling to walk," said Murray.Ferrer in quarters
Meanwhile, top seed and hometown boy David Ferrer eased into the quarter-finals of the ATP Valencia Open 500 tournament yesterday, beating Canadian qualifier Vasek Pospisil 6-3, 6-3.
Ferrer, ranked five in the world, will play Russian veteran Nickolay Davydenko in Friday's quarter-final.