Australia's Quade Cooper will be out of action for at least six months after rupturing the anterior cruciate ligament in his right knee during the third-place play-off win over Wales.
The 23-year-old limped off the pitch 22 minutes into the 21-18 victory.
Cooper will undergo surgery and miss the start of the 2012 Super 15 season.
He will also be absent for Australia's northern hemisphere tour later this year where they face Barbarians on 26 November and Wales on 3 December.
The injury marked a miserable end to the tournament for Cooper, who had belatedly showed signs of his best form after a series of below-par displays that saw him jeered throughout the Wallabies' campaign by New Zealand fans.
The Queensland Red, who was born in Tokoroa on New Zealand's North Island but moved to Australia as a 15-year-old, attracted controversy after a series of run-ins with All Black skipper Richie McCaw during this season's Tri-Nations campaign.
Cooper visited a surgeon in Brisbane to assess the injury, and later tweeted: "So got a torn ACL and having scans to determine no other injuries. Planing to have a traditional ACL surgery later this week."
The Wallabies' playmaker led the Queensland Reds to the Super 15 championship in 2011 and helped Australia win the Tri-Nations for the first time since 2001.
Will Genia, Cooper's half-back partner at for both the Reds and the Wallabies, is hopeful that his team-mate will bounce back from his injury and the reception afforded him in New Zealand.
"In terms of his character, he showed a lot of guts and a lot of character. He will be much better for it," said Genia.
"Obviously the way he finished with that injury is disappointing but he will come away a better person."