The Washington Nationals are happy Bryce Harper isn't showing signs of a concussion after a scary collision.

The NL batting leader's status is uncertain for the opener of a three-game road series against the Philadelphia Phillies, who are starting impressive rookie Aaron Nola on Monday night.

Harper, who has a .333 average and leads the majors with a .648 slugging percentage, was removed from Sunday's 5-0 win at Miami for precautionary reasons after colliding with Marlins second baseman Derek Dietrich while running the bases.

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''I tried to get up on my own, but I felt pretty dizzy,'' Harper said. ''Once I rolled I just said that I didn't feel right. I was looking up into the stadium and I just didn't feel good at all."

Harper does not have a concussion, though the Nationals (72-70) are unsure of his status.

"When we got out there, he reported a little bit of dizziness, so as a precaution we took him out,"manager Matt Williams said. "All tests after and since have been really good, no signs of a concussion so we'll keep evaluating him through the night and see how he is tomorrow."

Matt den Dekker replaced Harper and hit his third homer and Anthony Rendon had three hits to support Max Scherzer, who went eight innings as Washington stopped a five-game slide that has effectively ended its hopes of winning the NL East.

Washington has an 8-5 mark against Philadelphia (56-88) as it gets its first look at Nola (6-2, 3.56 ERA), who struck out seven in seven innings Tuesday for a 5-0 win over Atlanta that improved his record to 3-1 with a 2.10 ERA in five home starts.

"His ability to locate his fastball down in the zone on both sides of the plate is his strong suit," interim manager Pete Mackanin said.

The right-hander is about 15-20 innings short of his limit with a total of 170 pitched so far, including the minor leagues. He is scheduled for three more starts.

"It's obviously been my longest year so far," Nola told MLB's official website, "but I really feel good. My body and arm feel really good. Every time I go out I just try to go as long as I can."

He'll be opposed by Jordan Zimmermann (12-8, 3.32), who has a 4.67 ERA on the road compared to 2.47 at home. Zimmermann was in line to win his fifth straight start Tuesday after allowing one run in 5 2-3 innings before his bullpen blew a six-run lead in an 8-7 loss to the New York Mets.

The right-hander is 4-2 with a 2.33 ERA in his last six outings versus Philadelphia. Ryan Howard is 3 for 22 in this matchup.

Phillies second baseman Cesar Hernandez's status is uncertain after he dislocated his thumb in Sunday's 7-4 win over the Chicago Cubs.

Philadelphia continues to use young players, with left fielder Aaron Altherr going 2 for 3 on Sunday. Altherr is the first major leaguer born in Germany since Bob Belloir played shortstop for Atlanta in 1978, and 12 of his 19 hits have gone for extra bases.

''I just try to put the barrel on the ball,'' Altherr said. ''I'm trying to show them I can play here.''