Vice-captain Michael Clarke’s bad back has piled fresh uncertainty on Australia’s buildup to the Ashes cricket series while English is enjoying the advantage of an untroubled preparation.

Australian physiotherapist Alex Kountouris has confirmed that Clarke, who was unable to train with his teammates yesterday because of a back injury, is no certainty for the first match of the five-test series which starts at the Gabba ground on Thursday.

Late yesterday, the Australian selectors called uncapped New South Wales batsman Usman Khawaja to Brisbane as a standby in case Clarke is declared unfit. Khawaja had scores of 13 and 0 for Australia A against England in the four-day match which ended on Saturday but chairman of selectors Andrew Hilditch said his callup was deserved.

“As there is some doubt over Michael Clarke’s fitness for the Brisbane test match, it was felt prudent to bring a standby player into the squad,” Hilditch said. “Usman has been added as a result of his strong recent domestic form.

“We intend to give Michael as much time as possible to prove his fitness and a decision on his availability will be made in consultation with the team’s medical staff after the next two days of training.”

Clarke’s unavailability would load a new and weighty problem on an Australian team already hard-pressed by individual and collective form issues, selection doubts and the prospect of an opponent growing in confidence.

His degenerative back condition has troubled him through most of his test career. It flared when he played for New South Wales in Australia’s domestic Sheffield Shield competition 10 days ago and he was forced to miss the state’s latest match, which would have polished his personal Ashes preparation.

Koutouris said Clarke’s absence from training on Monday was part of a planned recovery programme and his state of fitness was being constantly monitored.

“He’s in the process of recovery now (and) part of the plan was for him not to have a bat today and hopefully he’ll be available for the game,” Kountouris said.

Australian captain Ricky Ponting said Clarke’s fate might be known as early as today.

“He’s been in this situation a few times in the last couple of years, he’s had these niggly things with his back and been able to come up most times,” Ponting said.

“If we don’t see him bat (Tuesday), then I think it will be hard to see him considered for the game,” he said. “It will depend on how much he is able to do tomorrow and Wednesday but someone as important to our team as he is we’d probably wait until Thursday morning.”