O’Neil has made just one appearance this season as he has been dogged by a troublesome knee injury but has trained all week after an injection in his knee.
Manager Gordon Strachan is waiting on several of his Scotland internationals.
Midfielder Barry Robson and striker Kris Boyd picked up knocks in the 2-1 win at home to Liechtenstein but winning goalscorer Stephen McManus is fine.
Tarmo Kink complained of a knee injury while on international duty with Estonia and could be a doubt but Mickael Tavares may make his debut at Loftus Road after signing on transfer deadline day.
Andrew Taylor and Jonathan Grounds left the club on deadline day so will not feature.