Paceman Brett Lee is adamant he will be able to start the third Ashes Test despite having to spend a second night in hospital with a knee infection.
Lee could join McGrath on the sidelines for the third Test
Lee experienced swelling and discomfort in his knee and was admitted on Monday but has responded well to treatment.
Australian vice-captain Adam Gilchrist told BBC Radio Five Live: "The improvement in 24 hours is amazing.
"I don't know what the experts have said but, just talking to Brett, he's certain he'll be turning out."
Lee is expected to be discharged on Wednesday before travelling to Manchester where his fitness will be assessed ahead of the Old Trafford Test.
"Brett was seen by doctors and they are happy with the progress of treatment so far," said Australia's physiotherapist Errol Alcott on Tuesday.
"The problem areas around his left knee appear to have improved."
The tourists have called up seamer Stuart Clark as a precaution ahead of Stuart MacGill, despite Old Trafford traditionally favouring spinners.
Gilchrist was also upbeat about the chances of Lee's fellow quick bowler Glenn McGrath, who was thought to have no chance of playing in Manchester after tearing ankle ligaments before the second Test at Edgbaston.
"He made an amazing recovery over the following 48 hours," said Gilchrist.
"He's improving at a good rate and he's definitely not 100% out of the game.
"He's certainly working hard to be part of the game."
Lee took four second-innings wickets at Edgbaston and almost batted Australia to victory with an unbeaten 43.
He was struck several times during his innings - but Alcott revealed Lee was feeling the injury prior to Sunday's exploits.
The soreness came from an old abrasion sustained in the first Test at Lord's and is just above the left kneecap.
"I checked him out on Monday morning and he was concerned about his knee," said Alcott.
"He was uncomfortable, it was swollen and it was very hot."
Alcott said of McGrath: "He had a scan on Monday for professional curiosity which disclosed extensive ligament damage which we were aware of when the accident occurred.
"We will now have to wait for the full medical evidence on the injury before we know how long he will be out of action."