Pettitte has been sidelined since July 17 with a strained left groin. He threw from a mound for the first time Friday afternoon.
Yankees blog
Pettitte, 38, said he may attempt to take a five-minute break in the middle of his Monday session to simulate sitting down between innings.
If all goes well Monday, Pettitte will throw either a simulated game or batting practice later in the week at the team's minor-league complex in Tampa.
"Nothing's set in stone, [it all depends] on how I come out of Monday," Pettitte said Saturday before the Yankees-Red Sox game. "But if everything's perfect that's what I would like to see done."
Pettitte ran Saturday afternoon and threw informally in the batting cage.
He did not want to put a date on his return to the Yankees' rotation. Pettitte will have to make at least one rehab start in the minor leagues prior to rejoining the Bombers.
"If I can throw in Tampa Thursday or Friday to some hitters and be able to sit down and get back up, we'll see how I feel arm strength-wise," Pettitte said. "Then we'll be able to talk about my rehab start."
The Bombers need Pettitte back as soon as possible. Sergio Mitre struggled in one start filling in for Pettitte and Dustin Moseley had one solid outing in place of the lefty but gave up five runs in 7 1/3 innings in his next start --- a loss to Toronto on Tuesday.
Ian Begley is a regular contributor to ESPNNewYork.com.
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