Ireland hooker Jerry Flannery is out of the Rugby World Cup after tearing his left calf muscle.
Flannery played the final 19 minutes after replacing Rory Best in Ireland's
22-10 victory over the United States
in New Plymouth last Saturday.
He suffered the injury on Tuesday at training and has been replaced by Damien Varley.
Ireland team manager Paul McNaughton said: "It is very disappointing for Jerry to have suffered this injury."
Tests revealed it could be up to six weeks before Flannery is able to play again.
And McNaughton added: "With the fact he is out for four to six weeks, we needed to make the decision to fly Damien Varley down as soon as possible.
"Sean Cronin will step into the replacements seamlessly this weekend which shows the importance of having experience and depth in the squad."
Ireland face Australia on Saturday at Eden Park, Auckland.