Oxford United striker Alfie Potter will be out for up to eight weeks with an ankle injury.
The 24-year-old was stretchered off during Saturday's defeat by Bristol Rovers and on Wednesday a scan revealed he has ankle ligament damage.
"It is a big blow because he is a big player for us. It wasn't the best challenge," manager Chris Wilder told the League Two club's website.
Potter has scored three goals in 13 appearances this season.