He is expected to make his next scheduled start, against the Phillies on Saturday.
Olsen fell to his knees, got up and bent over in pain. Head athletic trainer Lee Kuntz came to his aid, and a minute later, Olsen was taken out of the game and replaced by right-hander Garrett Mock.
Olsen also fouled off a ball that hit his right shin in the fourth.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.