Ten years ago, Andy Pettitte may have believed a strong bullpen workout was enough for him to make the next step and pitch in a minor league rehab game.

Now, 38, the lefty is encouraged by Friday’s developments but understands the process is about improvement.

“If it was up to me, let me go somewhere and throw,’’ Pettitte said after experiencing no problems with his left groin in a 40-pitch session. “I don’t think that’s going to happen. Probably throw another bullpen (Sunday) and figure it out from there. I need to push off on every pitch because for the first 15 or 20 I was a little hesitant.’’

Pettitte, 11-2 with a 2.88 ERA, has been out since leaving a game July 18 in the third inning. He has progressed from throwing on flat ground to two half-bullpens and Sunday’s full bullpen will be his second such workout.

“I want to get back but I don’t want a setback,’’ said Pettitte, who was told he would miss about five weeks when he got hurt. “Mechanically and command-wise I am doing everything I want to do. I felt great.’’

Pettitte said any rehab assignment would be more to gauge his stamina than stuff.

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According to Joe Girardi, Alfredo Aceves might throw in a minor league rehab game Tuesday for Scranton/Wilkes-Barre (Triple-A). Out since May with a back problem, the valuable right-handed reliever’s return would be a big boost.