Both players are headed back to Boston to see doctors and it is uncertain if they will be available for the Celtics' Feb. 28 matchup against the Cleveland Cavaliers.
The good news is Kevin Garnett is back and will play tonight. Celtics coach Doc Rivers said he will extend Garnett's minutes to 35, five more than usual.
Meanwhile, Rivers added that the team is likely to seek another big man if Wilcox and O'Neal are out for any extended period of time.
"It's pointing that way for sure," Rivers said. "But I think we'll find out more once Chris and JO get back, but the way they've been injured so much, we may need to get one anyway. I think that's something that Danny [Ainge] and I will talk over [during] the All-Star break. But listen, if there's a big out there, there's a reason he's out there. There's someone out there, we just don't know who it is yet."