Updated

Rangers striker Steven Naismith suffered 1 victory at Aberdeen and will be sidelined for the rest season, the Scottish Premier League club announced Tuesday.

Naismith, a Scotland international, leads Rangers and the SPL with nine goals. He has helped Rangers open a nine-point lead in the standings over Motherwell.

"This is devastating news for Steven and our thoughts are with him. He was in the form of his life and it is a huge blow for him and the club that he is out for the rest of the season," Rangers manager Ally McCoist said.

The 25-year-old Naismith sustained a similar injury to his left knee in 2008, and will have surgery on his recent right knee injury that will require up to nine months of rehabilitation.