Saini was unable to complete his eighth over, which came after lunch on day one of the series-deciding fourth Test, and has been sent for scans.

The fast bowler's reaction to a dropped catch from captain Ajinkya Rahane, who grassed a regulation chance offered by Marnus Labuschagne on 37, was telling.

Saini was seemingly more bothered by whatever went wrong in his delivery stride, immediately calling for assistance from team medicos.

The 28-year-old trudged off the field soon after, with Rohit Sharma completing the over.

Saini briefly returned to field during Friday's drinks break in the post-lunch session, only to limp back into the dressing room soon after.

"Let's see. We really wish he comes back and bowls the first over tomorrow," debutant Washington Sundar said.

India's hopes of retaining the Border-Gavaskar trophy, which they can achieve with a draw or win in Brisbane, would take a massive hit if Saini is unable to bowl again.

"It'll make a difference if we bat really big in the first innings and keep the bowlers out there," Labuschagne said.

"But they went in with the extra bowling option and it probably paid off for them, because they lost Saini early on."

Fast bowler Shardul Thakur also left the field in obvious discomfort late in the day.

The visitors' fast-bowling depth has already been tested in remarkable fashion this summer, as reflected by the fact that third-gamer Mohammed Siraj is now leading India's most inexperienced Test attack since 1946.

Spearhead Jasprit Bumrah was unable to prove his fitness for the final Test in Brisbane, where fellow quicks Mohammed Shami (arm), Umesh Yadav (calf), Ishant Sharma (side), Bhuvneshwar Kumar (thigh) are notably absent.

Australian Associated Press