(CNN) -- Britain's Andy Murray has suffered a blow in his preparations for the French Open as he was forced to pull out of next week's Madrid Open Friday.
The world number four, still chasing his first grand slam title, cited a back injury for his withdrawal.
"It is with regret that on doctor's advice I have to withdraw from the Mutua Madrid Open with injury," he told the tournament's official website.
"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 suffered a shock defeat at the tournament in the third round last season and had been hoping to make amends in the build up to Roland Garros.
Under new coach Ivan Lendl, the 25-year-old has reached the quarterfinals in Monte Carlo and Barcelona, but both times he was beaten by lower-ranked players -- Tomas Berdych and Milos Raonic.
He said he hopes to be fit to play in the Rome Masters later this month.
The $4 million tournament -- being played on a state of the art new blue clay court -- has already been hit by the withdrawals of American pair Mardy Fish and Andy Roddick.
But the top three in the world -- Novak Djokovic, Rafael Nadal and Roger Federer -- will all be in the Spanish capital.
Meanwhile, German veteran Tommy Haas continued his superb run in the BMW Open in Munich Friday.
The 34-year-old put out top seed Jo-Wilfried Tsonga in the last 16 and duly saw off Marcos Baghdatis of Cyprus 6-1 7-6 to win a place in the semifinals.
Croatian third seed Marin Cilic had a tougher battle against Mikhail Youzhny of Russia before beating the sixth seed 6-3 6-7 6-3.
Second seed Feliciano Lopez of Spain joined them in the last four by beating Australian youngster Bernard Tomic 6-4 6-2.
In the Estoril Open, top seed Juan Martin del Potro had a straight sets 6-2 6-2 win over Spain's Albert Montanes in their quarterfinal match.
Second seed Richard Gasquet of France also made it to the semifinals, beating Daniel Munoz-de la Nava of Spain 7-6 6-2.