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Andy Pettitte threw gingerly for the first half of a bullpen session, then ramped up his effort and said he will need more tests of his groin and stamina before returning to games.

The New York Yankees' left-hander was pleased with his progress in recovering from an injury that has sidelined him since July 18. Pettitte hopes to retest the groin Sunday, probably in a more intense bullpen. If all goes well, he'd be on track for a rehabilitation start after that and a return in late August.

He planned to speak with pitching coach Dave Eiland later Friday to go over the next step.

For the first half of his 35-40 pitch workout, Pettitte made sure to push off lightly on the left groin.

"I'm scared a little bit. I don't want to get hurt again, so just a little cautious," he said. "Each pitch I felt like I got a little more confident. So it was a good day for me."

A 38-year-old left-hander, Pettitte is 11-2 in 18 starts with a 2.88 ERA, a performance that earned him a spot on the AL All-Star team.

He lifted his legs with a little weight on Wednesday for the first time since sustaining the injury while throwing a pitch against Tampa Bay. He isn't feeling the strain.

New York's projection when he got hurt was a layoff of four-to-five weeks. He'll have to assess his stamina before he can guess when he'll be ready for a major league game.

"It's hard when they tell you five weeks or whatever," he said. "It just seems so long, you know, and now that you're 2½ weeks into it, you're like, 'OK, just don't have a setback.'"