Everyone in the Australian team may be under pressure ahead of the second Test against South Africa, according to coach Darren Lehmann.
But Peter Siddle looks set to feel plenty of pressure while out of the side after the veteran seamer withdrew from the Hobart Test with another back injury.
Siddle's playing future is again under scrutiny after scans on Tuesday revealed the 31-year-old had suffered a "likely" flare up of an old back complaint that sidelined him for eight months.
Jackson Bird is on standby as cover for the Hobart match but first Test 12th man Joe Mennie is tipped to replace Siddle in the XI.
It ensures at least two team changes for the second Test starting on Saturday with opener Shaun Marsh (broken finger) also ruled out.
But Lehmann reckoned everyone should be sweating on their spots after the 177-run first Test loss.
"I would say every spot is under pressure. That's the nature of the beast if you don't have success," said Lehmann after Australia's fourth straight Test defeat.
Siddle - a 62 Test veteran - will also be feeling the heat after being sidelined barely a month back from his lengthy injury layoff.
Australian team medical staff said they would know when Siddle could return "in the next week or so".
"Peter Siddle had some lower back soreness at the conclusion of the first Test," Australia team physio David Beakley said.
"This was slightly worse than we expected and given that he was returning from a significant back injury, we organised some scans today.
"The scans demonstrated some low grade bone oedema around his old stress fracture that is likely to be a flare up of his previous lower back injury.
"We are hopeful that this will resolve relatively quickly but have withdrawn him from the squad for the second Test Match in Hobart."
Siddle took match figures of 3-98 in the heavy first Test loss in Perth but his pace dropped below 130kph.
In only his second first class match back from injury, Siddle bowled on four consecutive days in Perth along with teammates Mitchell Starc and Josh Hazlewood.
But ex-Test quick Ryan Harris dismissed the notion that Siddle and recovering Test spearhead Starc were underdone in the first Test.
Starc is also on the injury comeback trail after suffering a nasty leg gash.
"They're probably better off being underdone than overdone, put it that way," Harris said.
"I used to always go into a game preferring to have not bowled as much because you want to be fresh.
"Should they have bowled a few more overs (before the first Test)? Maybe.
"But they wouldn't have played them if they didn't think they were ready."
Queensland's Joe Burns and South Australia's Callum Ferguson flew out for Hobart with Marsh out and a question mark over Adam Voges (hamstring).
Veteran batsman Voges and allrounder Mitch Marsh are now the incumbents under the most scrutiny ahead of the second Test.
