Sri Lanka were 3-31 at stumps on Tuesday after being set 410 to win the pollution-tainted third Test against India which was blighted by scenes of players vomiting on the ground.
Sri Lanka fast bowler Suranga Lakmal threw up twice in the morning session amid choking smog at New Delhi's Feroz Shah Kotla stadium, followed by Indian pacer Mohammed Shami later in the day.
Dhananjaya de Silva was batting on 13 and Angelo Mathews was yet to open his account when bad light stopped play on the fourth day of the Test.
Spinner Ravindra Jadeja struck twice in an over in the final session to rattle Sri Lanka's daunting chase.
The hosts, who lead the three-match series 1-0, need another seven wickets to claim victory.
Earlier, Rohit Sharma completed his half-century as India set Sri Lanka a daunting 410 to win the pollution-tainted third Test in New Delhi that saw paceman Suranga Lakmal vomit twice on the ground Tuesday.
The highest successful run chase in the fourth innings of a Test was by the West Indies who defeated Australia after making 418 in 2003.
Earlier, India skipper Virat Kohli (50) declared India's second innings on 246-5 after Rohit Sharma reached his half-century in the final session on day four at the smog-shrouded Feroz Shah Kotla ground.
Sri Lankan fast bowler Lakmal, who was forced to return briefly to the dressing room after vomiting twice while fielding, bowled 14 overs and claimed a wicket.
Groundsmen rushed in to cover the spot with sand and sawdust as air pollution in the Indian capital took centre stage for the fourth day in a row.
A doctor at the stadium examined three Sri Lankan players and said their vitals were normal.
For India, opener Shikhar Dhawan top-scored with 67 on a run-filled wicket. Lahiru Gamage, Dilruwan Perera, Lakshan Sandakan and Dhananjaya de Silva took a wicket each.
Sri Lanka had been dismissed for 373, conceding a 163-run lead to India, who had declared at 7-536. But it was the hazardous smog in one of the world's most polluted cities that again dominated proceedings.
The website of the US embassy in New Delhi showed the air quality index at 398, 15 times the World Health Organization's safe limit. Conditions were worse on Monday.
The Board of Control for Cricket in India said late Monday that New Delhi could be left off future fixture lists during the winter season when pollution in the region peaks.
BCCI secretary Amitabh Choudhary said venues would be reconsidered "in view of the situation which was encountered in the last two to three days."
"The BCCI has been sensitive on the smog and fog matter over the years."
India XI: Shikhar Dhawan, Murali Vijay, Cheteshwar Pujara, Virat Kohli (c), Ajinkya Rahane, Rohit Sharma, Ravichandran Ashwin, Wriddhiman Saha (wk), Ravindra Jadeja, Mohammed Shami, Ishant Sharma
Sri Lanka XI: Sadeera Samarawickrama, Dimuth Karunaratne, Roshen Silva, Angelo Mathews, Dinesh Chandimal (c), Niroshan Dickwella (wk), Dhananjaya de Silva, Dilruwan Perera, Lakshan Sandakan, Lahiru Gamage, Suranga Lakmal