Baltimore Orioles starter Jason Hammel left Friday night's loss to Detroit after injuring his right knee throwing to the first batter in the fourth inning.
Hammel took some warmup throws to see if he could remain in the game but was lifted instead for Luis Ayala.
"It's something he's been managing for quite a while," Orioles manager Buck Showalter said of Hammel's knee.
Showalter said the right-hander would have an MRI on Saturday afternoon.
"The good news right now is it doesn't seem to be swelling," he said.
Hammel (8-6) gave up two runs, five hits and a walk and had five strikeouts in his fourth straight loss.
The Tigers won the game, 7-2.