O'Neil has missed the last two games through illness but resumed training on Thursday and is expected to be available for the game at the Pirelli Stadium.
However, Kevin Thomson, who sat out Monday's 1-1 draw with Norwich after limping out of the New Year's Day fixture at Leeds with soreness in the leg he broke earlier in the season, remains a doubt.
Jonathan Franks returned to action as a substitute against the Canaries following summer back surgery and having impressed manager Tony Mowbray in training, will hope for further action.
But Stephen McManus (ankle ligaments), Willo Flood (knee), Rhys Williams (pelvis) and Matt Kilgallon (back) are still sidelined.
Source: PA
Source: PA