Australia head coach Andrew McDonald confirmed Cummins is "ready to go" following a back injury that ruled the home skipper out of the opening two Test matches of the series.
"His body's ready to go and barring anything else happening in the next week," McDonald said. "I'd be expecting Pat to be tossing the coin and putting the blazer on."
There was though not good news on Hazlewood, who will now play no part in the Ashes after suffering an Achilles issue following on from his hamstring strain.
Australia will now focus on getting the fast bowler fit and ready for the T20 World Cup that will take place early next year.
"Unfortunately, Josh won't be a part of the Ashes," McDonald said. "Really, really flat for him.
"A couple of setbacks that we didn't see coming, and we thought he would play a huge part in the series.
"It's a totally separate injury. It's somewhere lower in the calf to Achilles region. His preparation will then shift towards the (T20) World Cup, which is an incredibly important campaign for us."
The home side will also likely add spinner Nathan Lyon into the XI for the Adelaide Test after going with an all-pace attack for the pink ball encounter in Brisbane.
McDonald insists Australia still value the skills of Lyon despite the slow-bowler missing two of the last three Tests.
"We just value different things in the pink-ball game, and unfortunately, that meant Nathan had to be squeezed," McDonald said.
"That's nothing to do with his skill set. Not a reflection on where he's at from his own performance.
"It is a reflection on pink-ball cricket and a reflection on the surface that was presented to us."
Australia captain Pat Cummins will feature for the first time in the Ashes after being included for the third Test in Adelaide, while spinner Nathan Lyon also returns to the XI.
Australia batter Usman Khawaja says he is over his back injury and "ready to go" ahead of the third Ashes Test against England that starts in Adelaide in 17 December.
Australia wicketkeeper Alex Carey insists the hosts have not entertained any ideas of an Ashes clean sweep, reminding his side of the drawn series in England last time out.
Australia T20I captain Mitchell Marsh has announced that he will retire from first-class cricket but is still "open to the prospect" of representing his country in the longest format.
