Carlisle United striker Joe Garner could be out until Christmas after damaging his anterior cruciate ligament.
Garner suffered the injury during the midweek win at Crewe Alexandra and scans have shown up the problem.
Though Carlisle have yet to confirm how long the teenager will spend on the sidelines, reports suggest he will be out for around nine months.
Club physio Neil Dalton told Carlisle's official website: "The results show that the twist did cause some damage to the ACL, so we will refer him to our surgeon in Bingley for further advice.
"He will then decide whether the knee needs an operation or if some other form of rehabilitation will be more appropriate.
"We can't really comment any further on the injury until the surgeon has completed his examination."
Garner has scored 14 goals for Carlisle since arriving at Brunton Park for a club record fee from Blackburn Rovers last summer.