NEW YORK - Roger Clemens is being given an extra day to rest his left hamstring and was pushed back until Tuesday night in the New York Yankees’ rotation.

Clemens tweaked his hamstring while running Thursday and originally was rescheduled from Sunday to Monday. Andy Pettitte will now start Monday’s series finale against Toronto on regular rest, and Clemens will start the series opener at Tampa Bay.

“We hope he can pitch on Tuesday; we think he will,” Yankees manager Joe Torre said on Sunday. “We’re putting him back in his slot, which has been behind Andy all year.”

Clemens has pitched just once since Sept. 3, sidelined at first by a tender right elbow that required two cortisone shots. The 45-year-old right-hander pitched six innings at Boston on Sept. 16, allowing an unearned run and two hits in six innings.

The seven-time Cy Young Award winner threw a side session Sunday morning in the Yankee Stadium bullpen. Clemens said his leg felt “a little bit more fatigued than normal.”

“I felt really good yesterday,” Clemens said. “It feels a little different today because I’ve had a lot people digging at it and doing things to it.”

He said trainers Gene Monahan and Steve Donohue were pleased with his progress.

“I think that Geno and Steve consider it good that two spots showed up finally, which means the blood is coming to the surface,” Clemens said.

Clemens, 6-6 with a 4.18 ERA, said he’ll likely pitch with a wrap around his leg in his next start. He has at most two starts left before the playoffs, when he is likely to be part of a rotation with Chien-Ming Wang, Pettitte and Mike Mussina.

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“If I feel anything there, I’ve got to be honest. We’re in a real critical part of the season, obviously, right now,” Clemens said. “I don’t want to go backwards.”

Pettitte returned to the Yankees after going home to Texas to visit 12-year-old son Josh, whose hip was injured when he was sacked in a football game.

“He’s fine,” Pettitte said.

Pettitte is 14-8 with a 3.79 in his return to the Yankees after three seasons with the Houston Astros. He said he didn’t mind the switch, especially because his elbow is pain free.

“It’s just nice to feel like I don’t have to be eating anti-inflammatories the whole year,” he said.

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Pettitte’s deal with the Yankees includes a $16 million player option for 2008. He won’t think about that for a few weeks.

“I can’t even start really analyzing it because there’s so many things that I’ve got think about and run through with my family, and stuff like that,” he said. “As soon as we’re done here, I’ll start.”