Already beset with injuries to other key members of their lineup, the Nationals lost perhaps their most-important player to injury during tonight's game against the Braves: Bryce Harper.

The 20-year-old outfielder appeared to tweak something on a swing in the top of the sixth inning against Atlanta left-hander Paul Maholm. Harper remained at the plate and grounded the next pitch to first base. He ran only halfway down the line, then gingerly returned to the dugout.

Harper met with manager Davey Johnson and trainers in the dugout, then didn't take the field for the bottom of the sixth, with Roger Bernadina taking his place in right field.

He also hurt his left side slamming into the right-field wall on Tim Hudson's homer Tuesday night, leaving a long, nasty-looking gash, though it's unclear whether that was related at all to this injury.

The Nationals already went into this game without regular right fielder Jayson Werth (battling ankle and hamstring injuries) and third baseman Ryan Zimmerman (eligible to come off the disabled list Friday after straining his hamstring).