Britain's world number four Andy Murray has pulled out of the Madrid Open with a back injury, organisers said on Friday.
A winner of the tournament in 2008 when it was played indoors on a hard court, Murray reached the quarter-finals in 2009 and 2010 on clay court, and was knocked out in the third round last year.
"It is with regret that on doctors' advice I have to withdraw with injury," the 24-year-old said in a statement.
"I always love coming to Madrid so it is a big disappointment. I look forward to returning next year and wish everyone a great week of tennis."
The Scot, whose last match was a quarter-final loss a week ago on clay in Barcelona to Canadian Milos Raonic, informed officials of his situation a day before the men's draw.
This season has seen Murray play in just two clay-court tournaments, also reaching the quarter-finals in Monte Carlo.
Murray's quest to try and close a points gap on Roger Federer will fall by the wayside as he sits out the penultimate major prior to the May 27 start of the French Open.
Murray will need to race for fitness if he is to play in Rome, which starts a week from Monday.
The Madrid tournament was also hit Thursday by the withdrawal of US duo Mardy Fish and Andy Roddick, although the world's top three ranked players -- Novak Djokovic, Rafael Nadal and Roger Federer -- will be in the Spanish capital.