The Cincinnati Reds placed left-hander Nick Lodolo on the 15-day injured list Tuesday with a blister on his left hand.
The move is retroactive to Monday.
"It was a big deal he was able to pitch with that," Reds manager David Bell told reporters. "The good thing is it's not broken open. We just got to be sure it doesn't turn into something bigger than that."
Lodolo, 26, is 8-3 with a 2.96 ERA in 12 starts this season. He has struck out 73 batters in 70 innings.
Lodolo is 14-11 with a 3.