Bgles - Samoa back-rower Afa Amosa has been ruled out for the rest of the season with a serious knee injury suffered during the Rugby World Cup victory over Russia, the owner of his club Bordeaux-Begles Laurent Marti said on Friday.

Amosa, 28, left the field during the 34-9 win after scoring the Pacific Islanders' second try of the game.

"According to information received by the club's doctor Afa has suffered a tear to his anterior cruciate ligament and his medial cruciate ligament is also damaged," Marti said.

"He's unavailable for 8-9 months, so season over. Our doctor is in the process of bringing him to France so we can carry out the surgery here. On a sporting level it's a big loss," he added.

Samoa head coach Steve Jackson said earlier in the day uncapped Alamanda Motuga will replace Amosa in their World Cup squad and the seven-a-side specialist could feature in their next game in tournament against Scotland on Monday.

Bordeaux-Begles sit second in the French Top 14 table and travel to Montpellier on Sunday looking to maintain their unbeaten start to the campaign.

Due to Amosa's absence Marti's outfit could extend Masalosalo Tutaia's temporary World Cup cover contract to until the end of the season.