Australia fly-half Quade Cooper will be out of action for six months after rupturing the anterior cruciate ligament in his right knee during the Wallabies' 21-18 third-place play-off win over Wales.
The 23-year-old left the pitch 22 minutes into the game after pulling up during a run and falling to the floor in agony.
"[Cooper] will next week undergo an MRI scan before having surgery to reconstruct the ACL, while also repairing his lateral ligament," a statement from thr Australian Rugby Union read.
Cooper will miss the start of the 2012 Super 15 season and Australia's Northern Hemisphere tour later this year.
"So got a torn ACL and having scans to determine no other injuries. Planning to have a traditional ACL surgery later this week," Cooper tweeted.
Cooper had been the subject of much controversy throughout the World Cup after several run-ins with New Zealand skipper Richie McCaw.