Paine's captaincy and wicketkeeping were thrown into the spotlight following last week's shock 2-1 series loss to India, after two poor day-five performances.

The 36-year-old is almost certain to lead Australia to South Africa next month if the tour goes ahead, but it has not stopped questions being asked externally.

Chappell was one of Australia's selectors at the time Paine made the most unlikely of rises to captaincy following the ball-tampering scandal.

And while Paine put down three crucial chances in Sydney and another late in Brisbane, former Test captain Chappell said Australia must stand by their man.

"This is not the time to jettison Tim Paine," Chappell, who retired as a selector in 2019, told AAP.

"He's still the best keeper in the country and he's still averaged 40 in the Test series.

"Okay, he didn't have great games in the last two Test matches behind the stumps.

"But you can't overestimate how hard four Test matches in a row are, particularly for fast bowlers, and especially for a wicketkeeper-captain.

"It's an enormous workload and he probably suffered a little bit from the fact that he was pretty knackered by the end."

Despite regular questions over his batting, Paine's average of 32.63 remains the third highest of all Australian wicketkeepers.

Under his leadership Australia have retained the Ashes and won 11 of 23 matches, but have now dropped two home series to India.

Bigger questions remain over who could replace him, given Pat Cummins is the front-runner but no bowler has been the fulltime skipper since Richie Benaud in 1964.

Chappell meanwhile finds it harder to come up with a solution for the Test team's middle order.

While he is willing to forgive a tired bowling attack for failing to run through India in Sydney or Brisbane, he believes questions still revolve around the batsmen.

Matthew Wade has failed to reach 50 in his past 14 innings, while the BBL through the middle of the summer means no batsmen have been able to press their claims.

"I don't think there are many (solutions), to be honest," Chappell, who was on Tuesday appointed as an Officer (AO) of the Order of Australia, said.

"They're going to have to do something but it's going to be a bit of guesswork involved.

"I'm certainly not critical of the bowlers, I'm not overly critical of Tim. I think our batting certainly let us down."

Australian Associated Press