Nottingham Forest boss Steve Cooper says striker Taiwo Awoniyi will be out for "months" because of a groin injury.
The 26-year-old aggravated the problem playing for Nigeria during the international break and has had an operation on the issue.
Awoniyi has scored four goals in 10 Premier League appearances for Forest this season.
"We'll definitely see him again this season, but it's groin surgery so it will take a little while," said Cooper.
Former Liverpool forward Awoniyi is a key player for the City Ground side, scoring 10 league goals to help Forest achieve top-flight survival last season.