Barry was subjected to abuse during Tuesday's friendly at Walsall as Villa fans showed their displeasure at his attempts to engineer a move to Liverpool. It could get even worse for Barry if O'Neill feels the 27-year-old is in the right frame of mind to play in this weekend's European tie at Villa Park.
O'Neill said: "I think that in terms of fitness the game on Tuesday will have brought Gareth on so, if he's mentally tuned in and he wants to go and play, why not? Why shouldn't he be in contention for the game? He's a quality player and that's what we're looking for."
O'Neill's decision to put an £18 million (22.6 million euros) price tag on Barry has slowed transfer talks with Liverpool, but the Villa boss admits he is keen to resolve the situation one way or the other.
"We haven't heard back from Liverpool for some time and we're not exactly sure where we all stand," he said. "When people say people are in limbo, I don't think that applies to anybody more than ourselves. We don't know whether to move forward or not with it.
"It's a long-running saga and I wouldn't mind it ending one way or another. My preference - and hopefully I'm speaking for a lot of Villa fans, if not all of them - is that we would like Gareth to stay at the football club. That would be great because it will be hard to replace him.
"But we're not sure where Liverpool stand now. It was never mentioned before about them needing to sell some players before they bought - that was never in the system at all. But seemingly it must be part of it."
O'Neill hinted he could pull the plug on any further talks with Liverpool if they don't return with a new bid soon. "It's been unfortunate. We don't know where we stand at this minute," he added. "Liverpool have not officially come back to us in any form of writing. It is a really awkward position here at this minute.
"At some stage or other there will have to be a timescale on it because we cannot just keep going on like this. We have got our own plans to make - and we shouldn't be at the behest of Liverpool Football Club.
"We have to pick up the pieces and I could go on for forever and a day talking about it. It doesn't really matter. We have to see what develops."