Wallabies captain Will Skelton is in doubt for Monday's (AEST) Test against Fiji with a calf compliant.
Skelton was named for Australia’s second World Cup match, however, pulled up sore in the lead-up.
Watch every game of the Rugby World Cup LIVE on Stan Sport. Start watching Stan Sport now.
Wallabies officials confirmed on Friday the lock has a tight calf, with the team taking the precautionary approach of heading for scans.
Jones was tightlipped about the injury as he fronted the media without his skipper.
"He got a bit of a knock at the end of training and he is just getting some extra medical work," Jones said.
Nick Frost (ear) returns to the second-row and will likely partner Richie Arnold if Skelton is not fit, leaving either Matt Philip or Langi Gleeson to come onto the bench.
Jones refused to speculate on who would replace Skelton as captain, with vice-captain Tate still going through the concussion protocols.
It leaves returning prop James Slipper as the favourite alongside scrumhalf Nic White, hooker Dave Porecki and centre Samu Kerevi.
"We’ve got our next man up approach so everyone is prepared, that’s why we train so well together," hooker Porecki said.
"I think Eddie has covered it well. Their counter-attack threat across the park, they’ve got world-class players. We need to be switched on on Sunday."
Slipper's return to the side comes at the perfect time with Taniela Tupou ruled out with a hamstring injury.
He will join George Gregan and Adam Ashley-Cooper as the third Australian to play at four men's World Cups.
"It’s a remarkable achievement to play in four World Cups," Jones said.
"He started off as a tight-head then volunteered to go to loose-head. He’s volunteering to go back to tight-head. It’s a real testament to his courage, resilience, to how much he loves the game and he loves playing for the Wallabies.
"We think on Sunday he’ll play a pretty big game for us."
Fullback Ben Donaldson has also retained his position at the back, with Andrew Kellaway continuing to apply pressure.
"Kells (Kellaway) has been training well but Donno (Donaldson) played very well at fullback in the last game, kicked well, and we feel like we've got the necessary cover there," Jones added
