After two successful rounds of batting practice at Nationals Park the last two days, Bryce Harper will begin a rehab assignment with Class A Potomac tomorrow night.

Harper originally didn't expect to be ready to appear in a game until Wednesday at the earliest but bumped up the schedule after another strong BP session today at the ballpark, according to a source familiar with the Nationals' plan for the 20-year-old outfielder.

On the 15-day DL since late May with bursitis in his left knee, Harper has ramped up his baseball activities in recent days and put on a show during BP in front of fans Sunday morning. He returned to the park today for another hitting session in front of team personnel and emerged with no issues in his knee.

Harper plans to play three innings and start in left field tomorrow night for Potomac, then increase his workload each subsequent day. If all goes well, he could possibly come off the DL in time for some of this weekend's series at the Mets.