SAN FRANCISCO, July 22, 2008 (AFP) - Washington Nationals outfielder Wily Mo Pena had surgery on Tuesday to repair a small tear and fraying of the labrum in his left rotator cuff, the Major League Baseball team said.

The procedure was performed in Cincinnati, and Pena will be in a

sling for three weeks before beginning a rehabilitation programme.

He will be sidelined 4-6 months, but the Reds expect him to be ready for spring training next year.

Pena started having problems with his shoulder earlier this season. He received a cortisone shot roughly a month ago to relieve the pain and was placed on the disabled list Friday.

Pena had played through the discomfort, but is batting only .205 with two home runs and 10 RBI in 195 at-bats this season.