Defending champ Wawrinka out of US Open

NEW YORK (AP) Defending champion Stan Wawrinka has pulled out of the U.S. Open with an injured knee.

Wawrinka announced Friday he would sit out the rest of 2017 because of the knee.

He joins the man he beat in last year's final at Flushing Meadows, Novak Djokovic, in calling it quits for this season because of injury.

Wawrinka is a three-time major champion.

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