The Wallabies' front row stocks to face Fiji have taken a hit with key strike weapon Taniela Tupou under an injury cloud ahead of their crucial Rugby World Cup pool match in Saint-Etienne.
Tight-head Tupou was one of Australia's best in their tournament-opening win in Paris but didn't train with the team on Wednesday due to a hamstring complaint.
A Wallabies spokesman later said the powerhouse prop went for scans that night which showed a "minor hamstring injury" with no time-frame locked in for his return to training.
Australia already have props James Slipper and Pone Fa'amausili in doubt, with the pair missing the 35-15 victory over Georgia.
Slipper has been sidelined with a foot issue and was in and out of their session, seen in the early stages doing some boxing drills.
With Fiji losing their opening pool match against Wales, Australia are almost guaranteed a quarter-final berth with a victory on Sunday (Monday AEST).
Assistant coach Jason Ryles said Tupou hadn't been ruled out just yet.
The 27-year-old was key to Australia's dominance in the scrum against the Georgians while he also set up a second-half try, racing down-field before throwing a looping pass for Ben Donaldson to score.
"Taniela is on the sideline at the moment, he has got a bit of a hamstring complaint but we're going to monitor him and see how he goes over the next couple of days," Ryles said.
"He didn't train today but that's not unusual for Taniela, don't worry."
With 131 caps, Slipper is by far the most experienced player in the Wallabies camp, lining up for his fourth World Cup.
The 34-year-old loosehead has been wearing a moon boot as he tries to overcome a tendon injury in his foot while tighthead Fa'amausili has been battling a calf issue.
"Slips (Slipper) has been managed at this stage," said Ryles.
"He's certainly in the picture but we're not exactly sure how that's going to pan out, whether it's this week or next week.
"Himself and Pone have been doing a lot of stuff off field and then dropping into training at different stages with what their injuries allow them to and what the medical team allow."
With Australia taking on fellow big guns Wales in their third game, which could decide who tops the pool, coach Eddie Jones wants to get game time into Slipper against Fiji but can't afford to carry him on the bench if he's not 100 per cent.
Ryles said they weren't looking ahead to Wales, aware of the massive challenge posed by Fiji, who shocked England in their World Cup warm-up match.
"It's very cliched but all we've got on our minds is this week and how best we can prepare for that," the former Melbourne and Sydney Roosters NRL assistant coach said.
"We want to get our next couple of days right and play the best we can. We believe if we play near our best, then we're going to be hard to beat."
Jones is weighing up whether to again pick Donaldson at fullback or return to Andrew Kellaway when he names the team at 5.30pm Friday (AEST).
Looking to take the pressure off goal-kicker Carter Gordon, Donaldson got the nod against Georgia and booted six from seven but Kellaway is seen as a better defender which is key against the rampant Fijians.
Gordon was spotted doing extra goal-kicking practice at the end of Wednesday's training session so could be in line to take over the duties again.
Jones also needs to decide whether to start veteran halfback Nic White or rookie Issak Fines-Leleiwasa with first-choice Tate McDermott sidelined after a head-knock.