Pettitte has been sidelined since Thursday with back spasms, an issue that hampered his progress last spring as well. The 35-year-old left-hander has said that he does not believe this occurrence is as serious as it was last year, but he is still unsure if he will be able to throw in a scheduled bullpen session on Wednesday.
"I just can't get on the mound until I don't feel anything when I get over my front side," Pettitte said. "We'll start with playing catch and see how I feel. I think I'll know when I wake up if I can throw off the mound or not. You never know."
Pettitte played catch with pitching coach Dave Eiland for about five minutes on Monday, popping 47 tosses at a distance of 60 feet. He said he still feels tightness across his lower back on both sides, despite having been administered anti-inflammatory medication.
If he can get in a game by Friday, Pettitte would be available to pitch on April 2 against the Blue Jays, but if not, that projected start would be in jeopardy.
"It's definitely taking me a little bit longer than I thought it would when I originally hurt it, and that's definitely frustrating," Pettitte said. "I don't think it's anything other than a muscle spasm."
Yankees manager Joe Girardi said that Pettitte would not be scheduled for an MRI since the club believes it is just a muscular issue, and the club appears to be ruling out a stint on the disabled list.
"I don't think so, unless I do something stupid," Pettitte said. "They definitely have not mentioned that at all, so I don't think it's even in their minds. If it's not in their mind, it's definitely not in my mind."
Girardi said he took Pettitte's brief catch session as a positive sign.
"If you can play catch, it means it's not too painful and the back spasms are relaxing," Girardi said. "You see back spasms pop up pretty regularly during Spring Training because of increased intensity from what the workouts are during the offseason."
Girardi said that the Yankees' plan now is for Pettitte to be ready to throw a side session on Wednesday, which would allow him to pitch in a Minor League game on Friday in Tampa.
The Yankees have plenty of options to accommodate delaying Pettitte's 2008 debut, thanks to an off-day after the season opener on March 31. One plan being floated is that Mike Mussina could start on April 2 against Toronto, on regular rest, allowing Pettitte to pitch the Yankees' fourth or fifth game of the season that weekend against the Rays.
"We've got all kinds of options for me not to miss my first turn around," Pettitte said. "It's just a matter of if I pitch Game 2 or 4 or 5."
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.