India is unsure whether superstar Jasprit Bumrah will be available for the remainder of the fifth Test as the series against Australia hangs in the balance.
India's most potent bowler sent down just one over in the second session on day two before leaving the SCG pitch with back spasms around 1:20pm.
The best player on either side this series, Bumrah was then spotted entering a car in his training kit and being driven out of the carpark behind an ambulance to undergo scans.
The Indian medical team will assess Bumrah overnight as the visitors prepare to return to the crease on day three at 6-141, 145 runs ahead of their hosts.
"He had a back spasm," fellow quick Prasidh Krishna said of Bumrah.
"He has gone for scans so the medical team is monitoring. We'll know (whether he will keep playing) when the medical team gets back to us."
Any absence of Bumrah would raise significant questions over India's ability to win in Sydney and retain the Border-Gavaskar Trophy by drawing the series at 2-2.
While India bowled Australia out for 181 at tea on Saturday to claim a four-run lead, they will desperately want their strike bowler available for the last innings.
"He's an incredibly talented bowler," said Australian coach Andrew McDonald.
"If he wasn't to be there, India would have to come up with a new plan."
Bumrah's speed was well down in the over he did bowl on Saturday afternoon, with a mammoth effort across the first four Tests seemingly beginning to take its toll.
The 53.2 overs he bowled in the Boxing Day Test were the most he has sent down in any match of his career, with that fixture only finishing on Monday.
At one point on day four in Melbourne, Rohit asked Bumrah to bowl another, to which the quick replied: "Enough now, I'm not able to push more."
Bumrah has sent down 151 overs for the series, the most of any Indian player.
His bowling has kept his side in the hunt for the Border-Gavaskar Trophy, Bumrah's 32 wickets at an average of 13.06 the most of any Indian quick in one series.
The right-armer has already had to overcome injury concerns during the series, with treatment needed on his groin during his side's 10-wicket loss in Adelaide.
There had been concerns he would not be fit to play in the third Test in Brisbane, but the prodigious seamer was able to train freely in the lead-up to that match.
India's reliance on Bumrah has also been increased by the fact they have been without Mohammed Shami for the entire series, owing to long-running knee and ankle injuries.
Bumrah's exit on Saturday left former Test captain Virat Kohli to marshal the Indian side during Australia's first innings, with full-time skipper Rohit Sharma out of the team.
"No matter who is leading, as a team, we prepare really well about what we need to be doing," Prasidh said.
"The plan was pretty clear even when Virat was on."
Bumrah had taken 2-33 from his 10 overs before his injury, dismissing Usman Khawaja (2) on the last ball of day one before snaring No. 3 Marnus Labuschagne (2) cheaply as well.
