Lower-back pain prevented Shreyas Iyer from batting on the morning of day four, hampering India's efforts to match Australia's first-innings total of 480 in Ahmedabad.
On the third day, Ravindra Jadeja batted ahead of Iyer, which was not unusual - India frequently uses the left-handed Jadeja to break up a largely right-handed top order - Iyer did not come out to bat even after Jadeja was dismissed on the fourth morning. Instead, KS Bharat, a wicketkeeper-batter, came in at No. 6.
Soon after, the BCCI issued the following statement: "Shreyas Iyer complained of pain in his lower back following the third day's play (against Australia). He has gone for scans and the BCCI medical team is monitoring him: Board of Control for Cricket in India."
It is unclear whether Iyer will be able to bat at all in this Test match.
The injury will be especially concerning for India because back pain has plagued Iyer in recent weeks, keeping him out of the first Test of this Border-Gavaskar series as well as the three-match ODI series against New Zealand that preceded it.