Washington Nationals general manager Mike Rizzo said there was no ligament or tendon damage to Bryce Harper's left knee after he slipped on a wet first base during Saturday night's game.
Rizzo said Harper did suffer a hyperextended knee and bone bruise. The MRI on Sunday showed no apparent structural damage to the knee.
Harper is being placed on the 10-day disabled list.
Harper was limping but walking after the game. He was not made available to speak to reporters.
While running out a ground ball to the right side of the infield in the first inning, Harper avoided contact with first baseman Ryder Jones and his left foot slipped on the base. His leg buckled, he went airborne and fell to the ground as his helmet went flying.
Harper clutched at his left knee after going down and was attended to by trainers. The star outfielder put no weight on his left leg as he was helped off the field by hitting coach Rick Schu and head athletic trainer Paul Lessard.
The game began just after 10 p.m. following a 3-hour rain delay. It was raining steadily when Harper's injury happened.
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Major League Baseball was in control of weather decisions because it's the Giants' final trip to Washington this season. The series opener Friday was postponed after a lengthy rain delay to be a part of a day-night doubleheader Sunday, adding to baseball's incentive of getting the game in Saturday.
Even though first baseman Ryan Zimmerman is having an All-Star season, Washington's title hopes hinge largely on Harper's health. The 2015 MVP is having another spectacular season, hitting .327 with 29 home runs and 87 RBIs while playing in 105 of the Nationals' first 113 games.
Harper didn't last long in his 106th game and was replaced by Andrew Stevenson, who took over in center field with Brian Goodwin moving to right. Despite many fans waiting out the delay, the stadium went eerily silent in the minutes after Harper's injury.
Because of a bevy of injuries, the Nationals have used 12 outfielders this season. They have been without Adam Eaton since late April because of a torn ACL in his left knee that ended his season, Jayson Werth since early June because of a bruised left foot and Michael Taylor since July with a right oblique strain.
The Nationals are running away with the division despite those injuries and more to starters Stephen Strasburg and Joe Ross, relievers Shawn Kelley and Koda Glover and shortstop Trea Turner, but a long-term injury to Harper would be far more trouble to Washington's postseason hopes.
Harper is under contract through next season and can be a free agent in the winter of 2018.