Only three batsmen from Australia's current top six are locks for this winter's Ashes series in the UK, says Test great Ricky Ponting.

After a torrid series against India, Marcus Harris, Usman Khawaja and Marnus Labuschagne are the only certainties to be part of the squad to England from August 1, according to Ponting, while he expects the selectors to also persist with Travis Head.

Ponting says senior batsman Shaun Marsh must reverse his lean form if he is to be considered for England following a difficult series against India where he's averaged 26.14.

Outside the batters who have featured this summer, the former Test captain can see suspended duo Steve Smith and David Warner named in Ashes squad, especially if they return for the World Cup.

Harris is Australia's leading run-scorer in the series with 256 runs at 36.57, while Labuschagne looked textbook in scoring 38 on day three of the fourth Domain Test before he was out to a sharp catch by Ajinkya Rahane.

Head (237 at 33.85) and Khawaja (194 at 27.71) are Australia's most prolific batsmen after Harris this summer which has seen the home side fail to register a single century against India's potent all-round bowling attack.

"Harris is (a lock), I've been really impressed with the way he's played," Ponting told cricket.com.au

"Khawaja is a lock to go even though he hasn't had a great series so far.

"On the back of what I saw today I really liked what I got to see from Marnus. His technique looked good.

"He plays in Brisbane so he handles the swinging ball well which you sort of expect over in England so I'd pick him on the back of what I've seen today.

"Travis Head, our second leading run-scorer in this series but once again just lots of starts without going on. I think they'll probably stick with him.

"You've got to put some question marks over the others."

For veteran Shaun Marsh, Ponting says the left-hander simply must score runs if he is to be considered for his second Ashes tour.

Marsh has averaged 18 across 19 Test innings since his century against England 12 months ago in Sydney, and on Saturday was out for eight, edging an innocuous delivery from left-arm finger spinner Ravindra Jadeja to Rahane at first slip.

The manner of the latest dismissal left Ponting worried.

"He's averaging 34 in Test cricket and at his best he's very good," the former Australia captain said.

"We saw again today he started nice and positively and hit two really good cover drives and then it's just the ball that doesn't do anything that gets him out.

"You'd even sit back and question why he thought he had to play at that delivery. It was a fair way outside off stump and wasn't like it was going to spin back square and challenge his off stump, so why (did he) need to play at it?

"The fact that he played a straight one and nicked a straight one is a bit of a concern."

With Australia's batting order in a state of flux eight months out from the first Ashes Test at Edgbaston, Ponting is excited at the prospect of banned duo of Smith and Warner returning to action at the highest level.

Their bans lift at the end of March and will have a diet of white-ball cricket ahead of the Ashes in the shape of the domestic T20 cricket leagues and the 2019 Cricket World Cup, if selected.

Should they be named in the World Cup squad, Ponting expects Australia's two top-ranked Test batsmen to play against England.

"I think they will (make the Ashes squad)," Ponting said.

"I'm actually looking forward to seeing them both come back and see them play cricket for Australia.

"Obviously there's a World Cup to play first, so if they walk back into that side I'm pretty sure they'll walk back into the Ashes squad.

"We'll wait and see what happens there. I'm not the one making the decisions."