Oxford will wait on Johnny Mullins ahead of the visit of Exeter.
The defender was replaced by Ryan Williams just seconds into the second half during Saturday's 0-0 draw with Accrington after injuring his ankle in an awkward fall.
Mullins will be assessed by the club's medical team and manager Chris Wilder hopes he will be available to face the Grecians in the battle between fourth and third in Sky Bet League Two.
Wilder revealed striker Deane Smalley felt something flare up in his knee during the warm-up at the Crown Ground, which is why he remained on the bench throughout, and he will be monitored ahead of the trip.
Exeter boss Paul Tisdale could shuffle his pack as his side prepare for their second away trip in four days.
His team recorded an eye-catching 4-0 win at Scunthorpe on Saturday and the scorer of the last goal, Sam Parkin, is one of a number of players pushing for a start.
Matt Gill, the only current player involved in their memorable play-off semi-final victory at the Kassam eight years ago, could be handed his first start since returning to St James Park on loan from Bristol Rovers.
They will be without Danny Butterfield who has a calf injury while Matt Oakley will not play again in 2013 after suffering an ankle injury in the derby win over Plymouth.