From the official site:

Four days after Clemens pulled out of his scheduled season debut with the Yankees, he has been cleared to start Saturday's game at Yankee Stadium against the Pittsburgh Pirates. Mark it down, circle it, whatever. The Rocket is back. ...

Pettitte judged himself ready to start Friday's series opener against the Pirates after throwing a bullpen session before Wednesday's game. He suffered back spasms in his last start Sunday in Boston, and pushed back his bullpen a day.

"I threw, I felt good. I felt real good actually," he said. "I'm going to pitch Friday. I heated up and threw a good 'pen today."