Pace spearhead Jasprit Bumrah left the Sydney Cricket Ground midway through the second session on day two of the final Australia test on Saturday, possibly heading for hospital scans in a big setback for India.
The visitors need to win the match to retain the Border-Gavaskar trophy, with Bumrah their key strike bowler and skipper.
He left the field shortly before lunch, but reappeared after the break and bowled one over. But his speed was clearly down and he went off again.
TV pictures showed him in his training kit with medical staff, getting in a car and driving out of the ground.
Commentators suggested he was going for scans for an unknown injury.
Bumrah has taken 2-33 so far in Australia's first innings with the match finely poised.