BRISBANE, AUSTRALIA - DECEMBER 19: Indian players huddle during day three of the 2nd Test match between Australia and India at The Gabba on December 19, 2014 in Brisbane, Australia. (Photo by Cameron Spencer/Getty Images)

India could impose a selection bombshell ahead of the third Test against Australia in Indore, with former coach Ravi Shastri singling out struggling vice-captain KL Rahul as someone who could potentially be expendable come Wednesday's commencement.

Rahul hasn't had an ideal time of it as an opener, with rumblings building that the in-form Shubman Gill could be the man to upstage him if a change is to be made.

Shastri spoke on an ICC podcast recently, bringing into question the performance of the vice-captain and offering up the "red hot" Gill as a replacement.

"If the vice-captain doesn't perform, someone can take his place," Shastri said.

"I'm being blunt and brutal.

"Overseas, it's different. Here, you want prime form, you want someone like Shubman Gill, who's red hot."

Gill batted through a protracted net session on Monday, fuelling whispers that he'll be named an opener in place of Rahul, who was said to not have batted for as long.

Meanwhile, the Australians are preparing to embark on the third Test without skipper Pat Cummins, who has departed the team's base to be with family members amid his mother's battle with illness, with Steve Smith named stand-in captain for the Indore showdown.

Mitchell Starc looks poised to push through his finger injury, while Cameron Green and Scott Boland present as fast-bowling options for the selection committee to consider.

The third Test represents the second-to-last clash between Australia and India, with the Aussies needing to win each of the last two Tests in order to tie the series.