Oxford manager Chris Wilder's injury worries have increased with the news that Peter Leven will not be fit to face Swindon on Saturday.
Midfielder Leven has been playing through the pain barrier with a shoulder problem over the past few weeks and is set to see a specialist to assess the extent of the damage and decide whether he requires an operation.
Captain Jake Wright could also be missing for Wilder, who admitted he is frustrated by the situation.
He told the club's official website: "It is a blow but Levs has been playing through quite a bit of pain and it has reached a stage where he can't continue and we need to address the issue.
"The timing is not great, especially with Jake struggling with a back injury, but the crux of the matter is that he will not be fit for Saturday."