Pettitte hurled four scoreless innings in Trenton's 1-0 victory over New Hampshire, firing 51 pitches and scattering two hits while striking out four and throwing a pair of wild pitches.
The Yankees want to keep Pettitte on regular rest for his next effort, which would target him for Tuesday, but the scheduling is uncertain.
Trenton leads, 2-0, in its best-of-five series and could have Pettitte back if it advances to the next round of the playoffs. Class A Tampa would be playing Game 5, if needed, for the Florida State League title against Charlotte.
"Our hope for Andy is that both of the Minor League teams are still in it and he can make one more rehab start for us," Girardi said. "We're hoping the schedule cooperates."
If it doesn't, Girardi's contingency plan would involve a decision between burning Pettitte's five innings and 80 pitches in a simulated game, or having him take the mound on Tuesday against the Rays at Tropicana Field in place of scheduled starter Ivan Nova.
Girardi said that his inclination would be to lean toward the simulated game, but the manager noted that could change as the week continues.