Australia's top-order batters have struggled in the Border-Gavaskar Trophy but captain Pat Cummins has defended their performances, saying statistics aren't the only barometer.

"We are not beholden to stats," Cummins said.

"We know there are certain roles and easier times to bat and harder times to bat, just like bowlers. You are looking at the best seven batters as a unit to play the best you can."

With the series tied at 1-1, selectors will have big calls to make ahead of the fourth Test at the MCG.

Australia slumped to 7-89 before declaring on the final day in Brisbane, but Cummins said the innings could be dismissed as simply chasing big runs.

Usman Khawaja's stated desire to continue playing until next summer's Ashes series is looking far away as Australia's opening dilemma deepened in the drawn third Test against India at the Gabba.

The 38-year-old Khawaja was comprehensively bowled by Jasprit Bumrah for eight in the second innings and has now made just 161 runs in his last 11 Test innings at an average of 16.1. In this Border-Gavaskar Trophy he has just 63 runs at 12.6.

His opening partner Nathan McSweeney's early Test career woes continued when he played a wild shot outside off-stump to Mohammed Siraj and was caught behind for four. That dismissal needs to also be put in the context of Australia chasing quick runs to try and force a result.

McSweeney was asked by Australia's selectors to move from his No.3 position for South Australia to open for the first time in his first-class career in an attempt to find a long-term successor to the retired David Warner.

So far it has been unsuccessful with McSweeney scoring just 72 runs at an average of 14.4 although he has been taking the brunt of Bumrah's genius with the new ball just like Khawaja.

Cummins was asked whether McSweeney would be given the entire series as opener given his only score of note this series was the 39 in the first innings in Adelaide which was crucial in helping set up a big first-innings total.

"I think the selectors will get together tonight or tomorrow and pick the squad for the next couple of Tests but it has been hard for the opening batters for both sides," Cummins said after the Gabba Test.

"I have been impressed with the way (McSweeney) has gone about it. Today for someone starting out his career he was selfless to go out and try and play his shots rather than preserve (his wicket) and get a score.

"He probably hasn't got the runs he would have liked but he has played important knocks that have set up a win in Adelaide and a good result here."

No.3 Marnus Labuschagne also made a vital 64 in Adelaide but has only made 18 runs in his other four knocks of the summer. He had also passed 10 only once in his 10 knocks before the series.

Funnelling into the narrative around the failures of Australia's openers is the compelling case for a Test debut made by NSW prodigy Sam Konstas.

Australia's Travis Head, batting at No.5, has 409 runs and two centuries this series and has prospered when the ball has become softer.

Cummins said the current trend in Test cricket around the world is for the No.5 to No.7 batters to "score the bulk of the runs."