Australia captain Will Skelton was on Sunday ruled out of the Wallabies' Rugby World Cup Pool C clash against Fiji just one hour before kick-off in Saint Etienne.
Fellow lock Richie Arnold, who was originally named on the bench, was promoted to the starting XV due to Skelton failing to recover from a calf injury.
Matt Philip, who was not part of the original matchday 23, was named on the bench.
"Late change in Saint-Etienne with Will Skelton ruled out. Dave Porecki to lead us out against Fiji. Congrats skip," the Wallabies said on their official X account, formerly known as Twitter.
Skelton had been an injury doubt since limping out of training on Thursday, although the next day head coach Eddie Jones still picked him to captain the side.
The 31-year-old missed the traditional eve-of-match team photo on Saturday, with Arnold wearing his number five jersey and Philip included instead.
The Australian Rugby Union denied that meant Skelton had been ruled out, sparking accusations they were playing mind games.
"There's no mind games, we're just giving him as long as possible to get ready," lineout coach Dan Palmer had said on Saturday at the Geoffroy-Guichard stadium, where Australia and Fiji both took part in eve-of-match training sessions.
However, Palmer did confirm hooker Porecki would lead the side if Skelton was ruled out.
Skelton did briefly appear on the pitch ahead of the World Cup match, but he was hobbling and wearing heavy strapping.
Palmer had said he missed the team photo because he was receiving treatment from physios.
Sunday's clash is a must-win one for Fiji, who lost their Pool C opener 32-26 to Wales last week, while the Wallabies began with a 35-15 victory over Georgia.
Fiji have not beaten Australia since 1954 and only twice in 22 Test matches.
This is the fourth time in the last five World Cup tournaments that the two sides meet in the pool stage, with Australia winning all three previous clashes, including in Japan four years ago when Fiji led 14-12 at half-time before crashing to a 39-21 defeat.