Oxford United skipper Jake Wright is expected to miss the next month of the season with a hamstring injury.
The defender, who picked up the strain in Saturday's 2-2 draw with Gateshead in the FA Cup, will be joined on the sidelines by winger Alfie Potter, who needs ankle surgery.
"We were hoping, as Jake came off straight away, he might only be out for two weeks, but it will be four," boss Chris Wilder told the club's official website.
"Alfie goes in for an operation [on Thursday] to strengthen the ligaments in his ankle and will now be out for 12 weeks rather than the eight which was first diagnosed. They are obviously both big blows for us."
Oxford currently sit second in League Two.
