Harper to undergo MRI after being carried off with knee injury

The Washington Nationals' worst nightmare may be coming true.

Bryce Harper had to be carried off the field after suffering a knee injury when he slipped on first base running out a ground ball in the first inning of Saturday's game at Nationals Park.

After the game, manager Dusty Baker didn't have many details, but confirmed Harper hyperextended his knee and will undergo an MRI on Sunday. Baker also encouraged fans to pray the injury isn't serious.

The start of the game between the Nationals and San Francisco Giants was delayed by three hours due to a massive rain storm, leaving the field - and the bases - wet and slick when the teams finally began playing a little after 10 p.m. ET.

Harper's left foot slipped across the first-base bag as he stepped on it following his ground out. He went airborne after slipping and then fell to the ground, clutching his left knee. Teammates had to carry him off the field, and he wasn't putting weight on his leg.

Harper was replaced in the lineup by Andrew Stevenson, who took over defensively in center field while Brian Goodwin shifted to right field.

Washington is already missing several important players due to injury, including All-Star starter Stephen Strasburg, shortstop Trea Turner, and outfielders Adam Eaton and Jayson Werth. Eaton suffered a torn ACL on a similar play at first base back in April and has missed almost the entire season.

The 24-year-old Harper, who won the NL MVP in 2015, is in the midst of a stellar campaign for the division-leading Nationals. He leads his club in nearly every offensive category, owning a .326/.419/.614 slash line with 29 homers, 27 doubles, 92 runs scored, and 5.0 wins above replacement.