"I'll be fine for next start," said Oswalt, who is 23-2 with a 2.62 ERA in his career against the Reds.
Oswalt (6-11, 3.12 ERA) said he was fortunate the ball struck him on a boney part of his ankle, which lessened the swelling. Still, the area was bruised and painful on Monday. Oswalt was hit in the second inning of Sunday's 9-0 loss to the Pirates and managed to finish four innings.
"I knew it wasn't going to be good," he said. "I didn't know how long it was going to take, but I kind of started feeling it on my landing. I just worried about trying to change my mechanics and hurting something else. My mechanics have been good all year."
Oswalt said he will throw his routine bullpen session between starts, likely on Wednesday. He's one win shy of tying Joe Niekro for the franchise record of 144 career wins.