The Ashes: Australia captain Michael Clarke unsure if he will be fit for opening Test against England next month

Clarke's reoccurence of a back injury has put his participation in the first Test at the Gabba on November 21 into doubt

Australia captain Michael Clarke has admitted he is no certainty to be ready for the first Ashes Test against England in November.

Clarke has been ruled out of Australia's tour of India, where they will play the hosts in one Twenty20 and seven one-day internationals, due to his long-standing back injury.

The 32-year-old has been suffering with the problem for some time and it limited his participation in warm-up and limited overs matches while on tour in England this summer.

And Clarke has now refused to guarantee he will be ready for the first Test at the Gabba which begins on November 21.

"I'll say definitely not (a chance of missing), but at this stage, we can't predict how long it's going to take to get right," he told reporters.

"If you ask Alex (Australia physio Alex Kountouris), I'm sure he'll say there is that chance.

"For me personally, I'm trying not to look at that. It's about being nice and positive and working my backside off and getting myself right."

The timing of the limited-overs series in India has been questioned, with the final game of the tour to be played just 19 days before the first Test.

England, who hold the Ashes after their 3-0 series win earlier this year, arrive in Australia on October 25, but Clarke said there was no advantage for the tourists arriving ahead of the hosts.

"Every player's different. For me personally, the way to prepare for any series is to score runs in whatever form - it makes no difference," Clarke said.

"If I'm playing one-day cricket leading up to a Test series, it doesn't really make that much difference for me.

"My preparation is pretty similar. I bat in a similar way in one-day cricket as I do in Test cricket. We'll have time."

Meanwhile fast-bowler James Pattinson, sidelined by a back stress fracture, has ruled himself out of the first two Tests, but believes he could be back for the third in Perth in mid-December.

"I won't be back for the first Test, don't think I'll be right for the second," he said.

"But all things going well I could push for that WACA Test. If it's a bit green we could play four quicks up there, but I'll know more when I start bowling."