Celtics center Shaquille O'Neal appeared on the court briefly Thursday before the start of Boston's practice session.

O'Neal got up some shots, then retreated to the locker room with his teammates to watch film.

Celtics coach Doc Rivers remains confident O'Neal will be ready to go when Boston tips off postseason play.

"I do [think Shaq will play in Game 1], I can't guarantee that," said Rivers. "He's going to do a little bit today. We're not going to do enough -- we're going to walk through stuff so I could do today -- but [Friday] and [Saturday] are the big days for Shaq. He's going to try to get through practice and see what we can do."