Pettitte sat down three times during the session to simulate the changing of innings at Camden Yards, and said that training on a stationary bicycle has helped him maintain his stamina.
"I feel pretty good," Pettitte said. "I'm trying to push it as far as I can without feeling like I might injure something. I'll see the [team] doctor on Monday, and I feel quite sure that he'll release me to be able to go ahead and go at it."
Pettitte said that pitching coach Larry Rothschild and bullpen coach Mike Harkey have told him that his stuff is "pretty close to where [we] want it to be," which is an encouraging sign.
If the Yankees had the luxury of a full Minor League schedule, Pettitte would likely be eyeing a rehab assignment at this time, but instead they will have to cobble together his program at the big league level.
"We're just kind of going day by day here," manager Joe Girardi said. "He has to see the doctor on Monday, so that's kind of a big deal for us. He still has to cover bases and do all those things, and until he can run, he can't really do that. That's kind of a big day, Monday."
Pettitte said that he expects to be cleared to throw another simulated game of about 60 pitches this upcoming week at Fenway Park, but beyond that, he shrugs when asked about his upcoming program.
"I'll pitch whenever they tell me I'm ready," Pettitte said. "I want to pitch. I'm not going to be stupid, but I didn't think I was going to come back and be as sharp as I am.
"I thought it would take a lot of [bullpen sessions] and some game work, but since my command's been so good, I think everyone's been comfortable running me back out there with these simulated games as quick as we can."