WALTHAM — After a lengthy film session and practice Thursday at their facility in Waltham, Celtics coach Doc Rivers pronounced everyone ready to play in Saturday’s Game 3 against the Heat at TD Garden.

Most notably, Shaquille O’Neal – according to Rivers – will be able to make his playoff debut for the Celtics after missing the first round and first two games of the Heat series with a sore right calf. Rivers said Paul Pierce also will be able to play, despite a sore Achilles that cropped up during the Game 2 loss Tuesday night in Miami. Pierce, however, was held out of Thursday’s practice as a precaution.

“Everybody’s good,” Rivers said. “Everybody is feeling pretty good. Shaq went through practice. We didn’t do anything today, we just watched film and walked over [some] stuff. Then, the second unit worked on their stuff but right now, we expect every single guy, including Shaq, to play in Game 3.

“Honestly, today, [Pierce] could’ve played in a real game but we were not going to let him practice today because his foot, Achilles, is bothering him but he would be fine.”

Rajon Rondo (back) and Ray Allen (bruised chest) took part in Thursday’s workout and are also expected to be ready. The Celtics will practice again on Friday before taking on the Heat Saturday night, trailing the best-of-7 Eastern Conference semifinal series, 2-0.