Melbourne, Oct 10 : Australia head coach Andrew McDonald admitted that captain Pat Cummins' chances of playing in the Ashes opener are decreasing but insisted the fast bowler remains on track to feature against England this summer.

Cummins has been battling a back injury that has prevented him from bowling since July, and the Australian skipper resumed running this week after scans showed some improvement in the lower-back stress injury.

McDonald has not given up hope that Cummins could play the first Test in Perth, admitting Australia are now racing against time since Cummins has not yet been cleared to resume bowling.

"My view would be four, four-and-a-half weeks," McDonald said, speaking on how long Cummins needs to be bowling for before the Ashes opener on November 21. "Myself and Patty have spoken about that type of timeframe. Or else you start to bring in other risk factors ' a) you're not skill ready, b) soft tissue injuries then become a real risk."

"And if you were to do a soft tissue injury early in a series like the Ashes, then it's a long way back from where he's been. So we'll be mindful of all those risk factors," he added.

If Cummins is ruled out of the series opener in Perth, it could open the door for former captain Steve Smith to take charge, while backup quick Scott Boland would likely be the most sensible replacement for the fast bowler alongside regulars Mitchell Starc and Josh Hazlewood.

McDonald suggested that Cummins' injury outlook has actually improved in recent days.

"It's a big couple of weeks, we've added some variables into his training in the last couple of weeks and had a positive result there," he said. "There's some positive signs speaking to Patty over the last few days. He's a lot more optimistic. Those who have been through this type of injury (say) these things ebb and flow."

"One of the benefits with Patty is that he has had the ability to prepare for Test matches off shortened preparations. So if it was to be shrunken down, we'd be very confident that he would still be able to perform in the first Test.

"But the reality is, we're starting to get tight in terms of the times. We're still optimistic, hopeful, but this time next week, I think we'll be in a position to get better gauge on where he's at,' he added.

/IANS