Washington Nationals left fielder Bryce Harper will have surgery Tuesday to repair a torn ulnar collateral ligament in his left thumb and is expected to be out until at least early July, reports ESPN.com's Keith Law.
Harper, 21, was already on the 15-day disabled list because of the thumb injury.
Harper was injured when he slid head-first into third base after a bases-clearing triple in Friday night's victory over the San Diego Padres, but stayed in the game for an inning and then was replaced.
The oft-injured Harper missed 44 games last season because of a left knee injury.
Harper is hitting .289 with one home run and nine RBI in 22 games this season. SI.com STAFF: MLB Power Rankings: Braves take over top spot, AL West pair rises