Dan Carter has been forced to withdraw from New Zealand's team for their final Pool A match against Canada on Sunday because of a groin injury.
The All Blacks fly half had to leave the captain's run training session at Rugby League Park, Newtown, on Saturday after pulling up during kicking practice.
Carter was due to captain New Zealand for the first time in the absence of Richie McCaw, who has an injured foot.
Colin Slade will take Carter's place at No.10 while hooker Andrew Hore will be captain for the first time.
Piri Weepu moves from No.20 to No.21 on the replacements' bench, to cover the fly half position, while Andy Ellis takes the No.20 jersey.
Carter, who missed the earlier Pool A match against Japan with a back injury, will be further assessed by medical staff on Saturday night, with an update expected on Sunday.