Wallabies assistant coach Dan Palmer insisted the squad weren't trying to fool Fiji by not publicly ruling out Skelton with a calf injury, despite the giant second-rower missing their final training run in Saint-Etienne's Stade Geoffroy-Guichard.
He said they would give him until as late as possible to prove his fitness before Sunday's (Monday AEST) match.
"Absolutely (he's a chance to play) ... there's no mind games, we're just giving him as long as possible to get ready as he's an important part of our team and we're prepared to do that," Palmer said.
"It's only a minor strain, hence why he's still in the mix."
If Skelton is sidelined, Richie Arnold will take his place in the starting side with another lock, Melbourne's Matt Philip making his first Test appearance of the year off the bench.
Palmer confirmed 30-year-old Porecki , who made his Wallabies debut last year, would take over the captaincy duties,
Porecki made a one-game cameo for the NSW Waratahs in 2015 but, overlooked for opportunities, left Australian rugby to take up a contract with Saracens and then London Irish from 2016 onwards.
He returned home in 2020 and was unlucky not to make his Test debut in 2021 due to injury.
If called upon, Porecki will become the 88th Test captain and sixth this year following Michael Hooper, James Slipper, Allan Alaalatoa, Tate McDermott and Skelton.
Veteran prop Slipper, who has captained the team 12 times, felt Porecki was ideal for the role if Skelton wasn't able to play.
"Dave, if given the opportunity, he'll be superb," Slipper said of Porecki, who has played 16 Tests.
"The way he goes his business on the field as a player - he leads by example.
"He's one of those players who is really measured, composed and world-class at his craft.
"He's got the respect from the boys. Even today leading the captain's run, he did a superb job. Good captains find a way under pressure to stay composed and to lead and he does that well."
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