Outfielder Bryce Harper was not in the Washington Nationals' lineup for Monday afternoon's 6-2 loss to the Baltimore Orioles and likely will miss Tuesday's game because of soreness in his left knee, manager Davey Johnson told reporters.
Johnson said before Monday's game that an MRI performed on Harper's knee showed no structural damage but the slugger has been diagnosed with bursitis in the knee.
Team medical director Wiemi Douoguih said the outfielder has inflammation of the bursa sac in front of his knee, which he anticipates clearing up in a couple of days.
"We need to let it calm down," Johnson said, according to USA Today Sports.
Johnson said it's possible Harper could return as the designated hitter on Wednesday when the Nationals play the Orioles in Baltimore.
Harper said Sunday he didn't expect to miss any time and said the knee "probably won't get better until the offseason" and "I've just got to deal with the pain."
Harper aggravated his knee three times Sunday against the Philadelphia Phillies -- with two head-first slides in the first inning and then fouling a pitch off the knee in the third inning. He was limping throughout the game and was removed for a pinch runner after drawing a walk in the seventh.
Harper has already missed three games because of the knee that's been bothersome since he ran into the wall in a game against the Los Angeles Dodgers on May 13, a collision that also left him with a gash in the chin that required 11 stitches.
Harper is hitting .287 with 12 home runs and 23 RBIs.
Johnson criticized Harper on Sunday for his head-first slides.
"If he'd quit head-first sliding, he'd be a lot better off," he said.
Harper, however, differed with the manager on whether it would do any good to stop sliding head-first, saying the knee feels pressure either way.
"If I slid feet-first right now, my knee might pop and not be good," Harper said.
The Nationals on Monday also officially placed left-hander starter Ross Detwiler on the 15-day disabled list with a strained oblique muscle. The move was made retroactive to May 16 in the hopes that he can return to the rotation next Sunday.
Left-handed reliever Xavier Cedeno was recalled from Triple-A Syracuse. Johnson said Sunday he hasn't decided who will start Tuesday in place of Detwiler, who is 2-4 with a 2.76 ERA in eight starts this season.
Meanwhile, catcher Wilson Ramos, out since May 16 with a left hamstring injury, will miss another four weeks, Douoguih said.
Information from The Associated Press was used in this report.