CINCINNATI — Tomas Berdych has pulled out of the U.S. Open, saying he's been diagnosed with appendicitis and needs time to recover.

The eighth-ranked Berdych lost to Marin Cilic in three sets at the Western & Southern Open on Thursday. He tweeted on Saturday that he was diagnosed in Cincinnati.

"So I will be flying back to Europe for additional checks and treatment," he wrote on Twitter. "I need to take some time off to recover fully."

Berdych reached the semifinals at the U.S. Open in 2012.

The tournament also will be without Roger Federer, taking the rest of the season off to rehabilitate a surgically repaired knee. Rafael Nadal got back on court only two weeks ago after missing two months with a wrist injury.

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