The 21-year-old has been ruled out for nine months after a collision which saw him stretchered off late in Brisbane's 5-0 win over Albany Creek Excelsior on Tuesday night.

Lambadaridis tore his posterior cruciate and lateral ligaments.

The Melbourne-born midfielder, who has made five senior appearances for Roar, is contracted until the end of the 2014/15 campaign.

"George sustained a serious left knee injury against Albany Creek," Roar head physio Tim Oostenbroek said on Friday.

"He will be having surgery next week to reconstruct injuries to the posterior cruciate and lateral ligaments."