BOWIE, Md. -- About an hour and a half before Bryce Harper was to play his first rehab game with Double-A Harrisburg on Thursday night, he stood in the Prince George's Stadium outfield, having some long toss. He kept stealing glances up at the video board, which was showing the early innings of the Nationals' series finale against the D-backs.

Harper then went out and performed like a guy nearly ready to do more than watch his big league teammates.

A long and sloppy game prevented Harper from playing a full nine innings for the first time in three rehab outings, the first two of which came with Class A Advanced Potomac. But he played six innings of left field in an 11-6 win over the Orioles' Bowie affiliate Thursday and went 2-for-4 with a walk, a triple and two RBIs, displaying patience at the plate and flashing his typical all-out baserunning. He also completed a couple of defensive plays and did not appear to have any trouble with his left knee.

"First couple innings were very lengthy," Harrisburg manager Matt LeCroy said, explaining the decision to remove Harper early. "He had to score from first, he had the triple. He got on the bases and then a lot of time out in the outfield. It was just too long. He'd been out there 2 1/2 hours, 2:40, so it was sort of similar to playing a full game. But he looked good, swung the bat well, made a couple plays in the outfield. I thought he moved around good on the bases, so it was a good sign."

For the third straight day, Harper did not speak to the media. The Nationals said before his rehab began that he would not do so until completing a full game.

Earlier on Thursday, Nationals manager Davey Johnson said he wanted to see Harper play nine innings, then take Friday off before playing again on Saturday to "make sure that everything's going to stay calmed down."

That plan could allow Harper to take some at-bats against rehabbing Orioles left-hander Wei-Yin Chen on Saturday. He then would be on track to join the Nationals for Monday's series opener against the Brewers in Washington. Harper has not played in the big leagues since May 26 as he recovers from bursitis in his left knee.

"I'll take him whenever he's ready," Johnson said after Washington's loss. "I think we just need to talk to him, see how he's feeling. But [Friday] was going to be off, then he was going to go back to playing. So we'll just have to wait and see."

Nothing looked amiss for Harper on the bases. He ran at full speed, slid head-first on a pickoff attempt and then feet-first on a play at third, leading with the left leg in the same way that aggravated his original injury. His only issue was trying to keep his helmet secured to his head.

In the first inning, Harper fell behind right-hander Devin Jones 1-2, worked the count back full and drew a walk. He then scored without a play on Justin Bloxom's double into the left-center gap, reaching up to corral the headgear on his way to third.

In the second, Harper caught up to a high 0-2 fastball and scorched it over center fielder Kyle Hudson's head, shifting into high gear and losing the helmet as he tore into third for a two-run triple.

"I hadn't seen him play much, but I thought he was really aggressive," LeCroy said. "Scoring from first, that was a big one, then the triple. I saw some aggressive baserunning and kind of running like I'm normally used to watching him run."

Harper worked a 2-2 count against reliever Matt Bischoff in the third before smoking a liner that one-hopped to right fielder Garabez Rosa. He fouled out against Bischoff in the fifth and struck out swinging against Clay Schrader in the seventh.

Harper still hasn't been tested much in left field, where he played three innings on Tuesday at Potomac before serving as a designated hitter on Wednesday. He caught a towering fly ball and a line drive on Thursday and also fielded a couple of balls that made it through the infield, but all of the plays were routine.

Harper exited the game after his strikeout in the top of the seventh, but apparently expressed no discomfort with his knee.

"I asked him, 'How you feeling?'" LeCroy said. "He's fine. He's strong. He just needs to get the reps."