Australian opening bowler Glenn McGrath has a blistered heel and is in doubt for the second Test starting against England at Adelaide Oval today.
Australia's selectors have delayed naming the XI until McGrath's fitness is assessed this morning.
South Australian Shaun Tait, 23, or Queensland left-armer Mitchell Johnson, 25, would replace the 36-year-old McGrath, whose seven wickets in the first Test in Brisbane lifted his tally to 549 at an average of just 21.46 in 120 Tests.
McGrath missed Australia's only two losses in the five Tests in England last year. Torn ankle ligaments forced him to be a late withdrawal from the second Test at Edgbaston, where England won by two runs, and an elbow injury kept him out of the fourth Test at Trent Bridge, where England won by three wickets.
McGrath was optimistic about his chances of playing in the second Test of this series after he had two brief bowling sessions in Adelaide Oval's nets on Thursday. But the decision to review his fitness again on Friday morning was made after he had met later with chairman of selectors Andrew Hilditch and team officials.
In between the two bowling sessions, Australian captain Ricky Ponting said: "He had a quick bowl this morning with a bit of different padding on his heel and he had to go up and change … he's just gone out to have another bowl. We probably won't know on him until tomorrow morning, I'd imagine.
"I said yesterday you'd pretty much have to amputate his foot, I reckon, for him not to be out there in this game. He was in a lot of pain last game and we just got him injected and he got on with it.
"Yesterday morning he saw a podiatrist who has done a fair bit of work with him and he's changed his inner soles in his shoes to take a bit of the pressure away from it. So hopefully he comes through with flying colours today."
Ponting said McGrath had been 'absolutely pain-free' after having an injection during the Brisbane Test.
"Me knowing that, and him knowing that, should mean that won't worry him too much at all through the game," Ponting said.
"Hopefully he comes up all right today and we don't have to worry about injections and that sort of stuff going into the game. That'd be the ideal scenario.
"It is only a blister so they can't see why it's going to get any worse. It's something he's actually had for about 15 years of his career. It's just got a lot worse last week.
"We obviously aren't going to be able to go into the Test match with him unless he's 100 per cent and we can rely on him to get right through the game at his best. That's as simple as it can be, I guess. It will be hard to keep him out but he'll know within himself if he's not right."
Ponting also played down any queries over his fitness saying that he was ready to play. He was troubled by back spasms late in the first Test and had physiotherapy treatment and a massage on Thursday, and said he would be 'okay'.
The Australian skipper confirmed Brett Lee had a good session with Troy Cooley, the Australians' bowling coach, in the nets on Wednesday - 'going over all the things about his bowling and his runner-up and his rhythm'.
"I think Brett's pointed out in the last couple of days in the media that he was having a lot of trouble keeping his front foot up there in Brisbane," Ponting said. "Anyone who watched the game fairly closely would have noticed he bowled really wide on the crease a lot of the time just because he couldn't keep his front foot.
"When you're running in and trying to bowl as fast as he is, if you're not really certain about your footing then the ball can go anywhere, as has happened in some one-day games before when he's slipped on that front line.
"I know that was in the back of his mind up there, but he did steam in, in the nets yesterday and bowled a very good pace, and I'd expect he'd be able to carry that into this game."
