The Norwegian striker has missed the last six games after damaging medial knee ligaments in the victory over Everton at Villa Park in September.
"Big John trained with us on Tuesday. We did some running with him," O'Neill told the Birmingham Mail.
"I will have a word with John, I will have a word with the physios...we will see. He should be really ready to play now.
"Am I tempted to throw John straight in? I really would have to look at that.
"I think all the Premier League games are high intensity - or certainly that is your view of them beforehand, as they don't always turn out that way - but this is one game that we know will be high intensity.
"Carew says that in terms of fitness work, he has been pretty good. He has done a lot of stuff while his injury has been improving."