Despite feeling "a little stinger" in his left hamstring while on a long-distance run Thursday, Roger Clemens believes he'll be healthy enough to start tomorrow against the Blue Jays. "I think (tommorow's) a real possibility the way I feel," Clemens said after a workout yesterday. "With all the treatment, it should be good for (tomorrow)." Of course, as the Yankees found out earlier this year when a conditioning coach lost his job, hamstring injuries can be troubling. Several players, including today's starter Mike Mussina, have lost time to hamstring injuries. If Clemens can't pitch tomorrow, Andy Pettitte will start, Joe Torre said. Pettitte would still be on regular rest because of Thursday's off day.