Wallabies forwards Will Skelton and Wycliff Palu have been ruled out of the Rugby World Cup tournament with injury.

Palu had been battling a lingering hamstring injury and he was substituted at half-time against Uruguay while Skelton departed the Test midway through the second half with what appeared to be a serious shoulder injury. Skelton's injury was diagnosed subsequently as a pectoral tear, and he will consult a surgeon on his return to Sydney.

Hooker James Hanson will replace No.8 Palu in the squad while Sam Carter will take lock Skelton's place, with the introduction of Hansen seeing three specialist hookers in the squad after Michael Cheika opted somewhat controversially for just two - skipper Stephen Moore and Tatafu Polota-Nau - in the original 31-man roster.

Carter, a regular Wallabies starter before suffering a knee injury during the Super Rugby season, is currently playing for Bordeaux-Begles in the French Top 14 on a four-game deal and should be available ahead to play England in the Pool A blockbuster against England at Twickenham on Saturday.

"Both James and Sam have been part of the team at various stages this season and I am confident they will be able to step up and grasp the opportunity they have been given," Cheika said.

Cheika said he was "really gutted" for Palu and Skelton, whom he also coached at New South Wales Waratahs. "From a team perspective, they both play important roles in the side and it is disappointing that we need to replace players in our squad."

Palu, 33, may not now play another Test as he was most unlikely to feature again the World Cup having slipped behind McCalman and David Pocock in Michael Cheika's back-row thinking. He has played 57 Tests for Australia, but he has has signed to play in Japan next season so will not reach the Wallabies' 60-cap threshhold for overseas-based internationals.