Leeds United striker Kemar Roofe suffered knee ligament damage in Wednesday's win over Swansea City, the club has confirmed.
Roofe suffered the injury during the 2-1 win over Swansea at Elland Road last week with scans on Monday morning confirming the extent of the problem.
The club have not yet put a timescale on the 26-year-old's period of recovery but say the player will work with the club's medical team at Thorp Arch to return to action as soon as possible.
A club statement said: "Leeds United forward Kemar Roofe will face a period on the sidelines following confirmation that he damaged knee ligaments during the win over Swansea City at Elland Road.
"Roofe will work hard with the medical team at Thorp Arch to return to action as quickly as possible."
Roofe has scored 14 goals for Marcelo Bielsa's side in all competitions so far this season.