The 6'4" defender, who can also play in midfield and is currently playing for Notodden FK in Norway will more than likely start after an injury to Darren Moore.
Davey told Barnsley Player:
"O'Neil will play against Manchester City tomorrow. He has been in training this week and has done well. He has played alongside Jamal (Campbell-Ryce) with Jamaica and comes highly recommended. He has been in for a couple of days and has done pretty well. Unfortunately, the injury to Darren (Moore) means we will have to throw him against Manchester City when we probably would have waited to see him in a game next week.
"He currently plays in Norway but we have been given permission to have a look at him and he would be available for a fee. He is not the defender we've been chasing but we will have a closer look tomorrow. He is 6'4" with decent pace and has experience of playing in World Cup Qualifiers and the Gold Cup. We will see what he can do tomorrow".