Rafael Nadal was treated for a stomach muscle problem during his third-round victory at the U.S. Open on Sunday.

The No. 3-seeded Nadal beat No. 32 Nicolas Almagro 7-5, 6-4, 6-4 in an all-Spaniard matchup.

Nadal already was comfortably ahead when both he and Almagro received treatment from trainers after the third game of the third set. Nadal had a patch applied to his stomach, while Almagro had his back worked on.

Nadal wouldn't discuss his health afterward.

"I don't want to talk about injuries," he said. "Sorry. No, no. I am a little bit tired to talk about injuries."

Nadal is a six-time major champion who is trying to complete a career Grand Slam by winning the U.S. Open.

This is his first Grand Slam tournament since the French Open, where he was upset in the fourth round, ending a 31-match winning streak at Roland Garros. He decided to skip Wimbledon, blaming tendinitis in his knees.

Nadal returned to the tour in August after about a three-month absence, and he appeared to pick up an abdominal injury then, although he pronounced himself fine when he arrived in New York.

Whatever the extent of his discomfort, Nadal played quite well against Almagro. Next up is a fourth-round match against No. 13 Gael Monfils.

"I came here and I know everybody wants to talk about the injury," Nadal said at his postmatch news conference. "I really don't want to talk about that."

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