Rangers have confirmed that Steven Naismith has been ruled out for the rest of the season with anterior cruciate ligament damage.
The midfielder underwent scans on his right knee yesterday and has been told he faces eight to nine months on the sidelines.
Naismith, who has netted nine goals for the Scottish champions this term, suffered the injury during Saturday's 2-1 win over Aberdeen in the Clydesdale Bank Premier League.
Naismith appeared to twist his knee while challenging Rob Milsom during Saturday's clash at Pittodrie.
He attempted to play on but collapsed to the turf with no-one near him moments later.
The 25-year-old sustained a similar injury to his left knee in 2008 and was out for eight months.
A statement from Rangers read: "Scans have confirmed Steven Naismith sustained an anterior cruciate ligament injury to his right knee during Saturday's game against Aberdeen at Pittodrie and he will sadly miss the rest of the season.
"Steven will be seen by the same surgeon who successfully treated him in 2008 and his rehabilitation programme will be 8-9 months."
Manager Ally McCoist backed Naismith to come back from the latest injury in the same way he did last time.