BANGKOK — Rafael Nadal has pulled out of the Thailand Open due to an injury sustained at the U.S. Open earlier this month.

Nadal was advised by his doctor to withdraw from the Sept. 26-Oct. 4 tournament to recover from a stomach muscle problem, Suwat Liptapanlop, president of the Lawn Tennis Association of Thailand, said Monday.

An ultrasound found that Nadal had an "acute rupture of his right abdominal muscle" that will require physiotherapy, rest and medication for "two to three weeks," the chief doctor of the Spanish Tennis Federation said in a statement released by tournament organizers on Monday.

Nadal lost his U.S. Open semifinal in straight sets to Argentina's Juan Martin del Potro, who went on to capture his first Grand Slam title with an upset victory over top-ranked Roger Federer in the final.

Nadal was forced to skip a title defense at Wimbledon due to sore knees that kept him off tour for all of June and July.