Paine, who turns 35 next month, was named captain after former skipper Steve Smith was handed a one-year ban in March 2018 for ball tampering and the wicketkeeper became the first Australian captain after Steve Waugh to retain the Ashes.

Smith's explosive return to the Test side, where he scored 774 runs in the Ashes, triggered calls to restore him as captain and Paine said talk about who eventually takes over was bound to happen, especially considering his age.

"It might be (my last summer), I'm not too sure," Paine told reporters.

"But... I'm enjoying doing it. I feel good physically, mentally. So while that continues, I'm scoring enough runs and keeping well enough, then I'd like to continue.

"I know when you get to my age that can change really quickly. I'm really looking forward to this summer, beyond that I haven't looked too far. I know what I want to do and what I want to achieve.

"I think when you're the Australian captain and the Australian keeper, they're two of the most critiqued roles in Australian sport and at the moment I have to hold them both. I know I'm going to be in the crosshairs for people all the time."

Paine said Australia's top priority now was to return to the top of the Test rankings and win the World Test Championship. Australia are ranked fifth in the world and trail leaders India by 244 points in the WTC standings.

"Our goal is to get back to that No.1 ranking and we want to win that Test Championship," he added.

"To do that we're going to have to be good enough to win in India and we're going to have to be good enough to beat everyone, everywhere.

"It's the only way we're going to get to where we want to get to. It's an exciting period and I'm looking forward to being part of the start of that and there is no end point at the moment."

Meanwhile, Paine has accused England star Ben Stokes of using Australia opener David Warner to sell his new book.

Allrounder Stokes has claimed in his new read On Fire that his stunning third-Test display in the Ashes series were motivated by Warner's constant sledging as he smashed a brilliant century at Headingley.

"He just wouldn't shut up for most of my time out there," Stokes said of Warner in a passage of the book.

But asked whether it was a cheap shot by Stokes, Paine said: "Oh, absolutely.

"I was obviously standing next to David the whole time and you are allowed to talk on the cricket field.

"But by no means was he abusing him or sledging him. It just seems to be a common trend in England that they like to use Davey's name to spike book sales. So good luck to them."

Australia play Pakistan in the first of their two Tests starting on Thursday in Brisbane.

Australian Associated Press