Washington Nationals slugger Bryce Harper is set to undergo surgery on Tuesday to fix a torn ulnar collateral ligament in his left thumb, according to a source close to situation.

"Bryce Harper will undergo surgery Tuesday to repair a torn ulnar collateral ligament in his left thumb and is expected to be out until at least early July, according to sources," via Real GM.

Harper, who is hitting .289/.352/.422 with one home run and 9 RBIs this season, will likely be out until early July to give more time to rehabilitate his surgery repaired thumb. Harper suffered the injury in the game against the San Diego Padres.

"I slid into the bag and I caught it a little bit," Harper said via ESPN. "Went into the dugout, swung a couple in the cage, felt fine. Went out to the outfield, it swelled up a little bit. ... So I got in and got some treatment on it."