After kicking off his rehab assignment at high Single-A Potomac and playing two games with the P-Nats, Bryce Harper has moved on to Double-A Harrisburg. Harper has joined the Senators for their four-game series against Bowie, allowing him to jump up a level while also staying local. Harper, who is rehabbing from left knee bursitis, is scheduled to play 8-9 innings tonight, according to Nationals manager Davey Johnson. Assuming all goes well over these next few days and Harper doesn't suffer any setbacks, Johnson said Harper's on track to return to the Nationals on Monday, when they open a three-game set against the Brewers. "I'd like to see him do nine innings (today), and then probably take tomorrow off and go back and play again (Saturday)," Johnson said. "Just make sure that everything's gonna stay calmed down." Johnson said he's a little concerned about what could end up being damp field conditions at Bowie. Harper played three innings in left field on Tuesday and was scheduled to play left again last night, but was moved to the designated hitter spot due to the wet field in Woodbridge, Va. The Nats hope that the field in Bowie doesn't retain much water, which will allow Harper to run around for most of the game in the outfield without any added fear of his knee being at risk. Harper fouled a ball off his foot during an at-bat last night, but Johnson said the 20-year-old came out of the game just fine. "A bunch of Mother Hens down there," Johnson joked. "Foul a ball off your foot, come out of a game. You kidding me? Like he's important or something."