Rivers said before the session that O'Neal's ability to play Tuesday likely rests on his soreness level after Monday's activity.
"That's the whole key, whatever we do today, if his body doesn't react well, you just can't play him," said Rivers. "I'm not going to take that risk for him."
But if O'Neal's body does react well to Monday's activity, and if the Celtics decide to forego the three offdays of rest that await before Saturday's Game 3, the 39-year-old center could very well be back on the floor Tuesday night at American Airlines Arena.
Rivers did caution that O'Neal hasn't engaged in much running, a hurdle he quite obviously has to clear to get back into game action.
"About as much as you and I have been running and I'm just going to take a gamble and say that's very little," Rivers joked with a reporter when asked how much O'Neal has been able to run recently. "I know from my point, I don’t know about you. He’s run a little bit. We have that [treadmill] in our facility that takes all the weight off, so he’s running on that every day. I don’t know if that counts, but he’s been doing a little running."