Clemens, 6-6 with a 4.45 ERA this season, left a Sept. 3 start against Seattle after four innings because of elbow discomfort caused by a change in his mechanics, the result of a blister on his foot. He returned home to Houston and had two cortisone shots in his elbow on Sept. 5. Tests also revealed ligament damage to the elbow.

The 45-year-old Clemens said today's 40-pitch session was crisper than the one he had Tuesday, when he threw at about 80 percent.

"It's not a game situation type of scenario, but it was a more violent pen than I would normally throw," Clemens said. "I'm pleased with it. My foot is holding up fine. For me, that's where it starts and ends as far as getting over my arm issues."

Clemens, who has never had elbow problems before, said he's eager to see how he responds to being in a game again.

"I'll push by body until it pulls back a little bit," he said. "All I can do is hope and trust that the doctor got the right spot and listen to, not only guys here, but other guys that have had elbow issues and cortisone shots."

Yankees manager Joe Torre and pitching coach Ron Guidry, who watched Clemens throw, were pleased with what they saw.

"He seemed fine," Torre said. "We'll wait, obviously, until tomorrow and see how he comes in. It looks like he'll be all right."

Clemens, who threw while at home in Texas before rejoining the Yankees in Toronto, said he's looking forward to returning to Fenway Park, his home as a Red Sox from his rookie year in 1984 until he left Boston following the 1996 season.

"I enjoy playing there," Clemens said. "I don't know how long it's been but I look forward to it. Boston is a team we're going to see more than these three games. When you have two teams that are very good at what they do and fighting for the same thing, it always makes for some excitement."

Mike Mussina started in Clemens' place against Toronto on Wednesday, his first start since Aug. 27, and beat Toronto with 5 2/3 shutout innings. It was his first win since Aug. 11 at Cleveland.

Rookie Phil Hughes, who beat Toronto Tuesday, is expected to pitch Sunday if Clemens can't go.