Pettitte said his back locked up while driving home after working out Thursday. He expects to make his next start Thursday and be ready for the regular season.
"I feel a lot better today than I did yesterday," Pettitte said. "Yesterday the middle of my back was locked up all the way down. Today, I just feel a little tight down in my lower back."
Pettitte also missed his start March 12 with minor muscle irritation on the outside of his left elbow.
Yankees manager Joe Girardi said he is not concerned about the injuries.
"No, because they've both been minor," Girardi said.
Pettitte hopes to play catch Sunday.
"Hopefully it will clear up quick," Pettitte said. "I still plan on making my first start of the season."
Yankees second baseman Robinson Cano didn't play in Saturday's game because of body soreness.