Harper, who was 3-for-3 with a walk and two RBIs, was able to walk off under his own power. Manager Matt Williams said after the game it was a precautionary move.
"Given the state of that game, get him out and get some ice on him right away," Williams said. "Hopefully he's good to go [Sunday]."
Harper was replaced by outfielder Matt den Dekker and was the third Nats' batter to be hit by a pitch during the game. Brewers manager Craig Counsell denied that it was intentional.
"That's just a ball that got away," Counsell said. "That's the one chance you had to really go after him and get him out. It was probably our best chance of the day to really go after him."
Harper entered Saturday leading the Major Leagues in walks (51), slugging percentage (.721), OPS (1.190) and was second in home runs (22).
Brandon Curry is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.