WASHINGTON -- Nationals right fielder Jayson Werth had left wrist surgery on Monday. He is expected to be out at least 12 weeks. It is believed a steel plate was inserted in his wrist.

The procedure was performed by Dr. Richard A. Berger, a hand surgeon and professor of orthopedic surgery at the Mayo Clinic in Rochester, Minn. Dr. Berger repaired a displaced left distal radius fracture.

Having wrist problems is nothing new to Werth. He broke the same wrist as a member of the Dodgers in 2005, and he ended up missing all of 2006 because of the injury.

Neither Werth, nor manager Davey Johnson or general manager Mike Rizzo were available for comment.

The injury occurred in the top of the sixth inning on Sunday against the Phillies, when Placido Polanco hit a blooper to right field. Werth dove for the ball and his wrist was bent backward. It looked like he caught it, but the ball came out of his glove for a single.

Werth was in immediate pain and left the game a few minutes later. He was replaced by Xavier Nady, who is dealing with an injury to his left side.

With Werth out, Johnson plans to platoon Nady and Roger Bernadina in left field, while Bryce Harper will be the everyday right fielder. Johnson also said Stephen Lombardozzi and Chad Tracy could also see action in left field.

The news of Werth's injury comes at a time when the Nationals were expecting to get healthier. Third baseman Ryan Zimmerman is expected to be activated from the disabled list on Tuesday, and first baseman Adam LaRoche is hoping to be back in the lineup after missing a few games because of a right abdominal injury.