Sri Lanka grabbed three big wickets in the closing session to throw the second Test against India wide open on the third day in Galle today.
India were strongly placed at 1-144 before slipping to 4-200 in their second innings at stumps, with Muttiah Muralitharan, Ajantha Mendis and Chaminda Vaas sharing wickets.
After claiming a 37-run first innings lead earlier today, the tourists are now 237 ahead with six wickets in hand.
Sourav Ganguly and Venkatsai Laxman had yet to open their accounts when bad light stopped play.
India appeared to have seized the initiative after attacking knocks from Gautam Gambhir (74), Virender Sehwag (50), Rahul Dravid (44) and Sachin Tendulkar (31) before losing their way.
Sri Lanka were bowled out for 292 in their first innings on the stroke of lunch in reply to India's 329, with skipper Mahela Jayawardene top-scoring with a stylish 86.
Off-spinner Harbhajan Singh played a big role in India gaining the lead as he grabbed 6-102 for his 22nd five-wicket Test haul.
He was brilliantly supported by leg-spinner Anil Kumble (3-81).
Left-handed Gambhir and Sehwag gave India a flying start for a second successive time in the match, adding 90 for the opening wicket. They had put on 167 in the first innings.
Sehwag again showed the way as he followed his first-innings 201 not out with a blazing fifty, blunting the Sri Lankan spin attack with his aggressive approach.
He reached his fifty off 49 balls before he fell playing an uppish drive off paceman Vaas, with Tillakaratne Dilshan timing his jump to perfection to take a superb catch in the covers.
Gambhir, who made 56 in the first innings, also used his feet remarkably well against spinners Mendis and Muralitharan to complete a second successive half-century.
He had been batting fluently before being bowled by Mendis, attempting to pad away a delivery that turned in sharply to hit the off-stump.
Sri Lanka bounced back into the match when they dismissed Tendulkar and Dravid in the space of eight deliveries.
Tendulkar was caught in the slips driving an away-going delivery from Vaas, while Dravid was adjudged leg-before off Muralitharan.
Dravid was initially given not out by umpire Billy Doctrove of the West Indies, but the Sri Lankan captain requested the official to review the decision under a new experimental rule which is on trial in the series.
Doctrove changed his decision after consulting TV umpire Gamini Silva of Sri Lanka.
The Indian spinners earlier shattered Sri Lanka's hopes of gaining the lead by sharing five wickets, with Kumble taking three and Harbhajan two.
The hosts could add only 77 to their overnight total of 5-215.
Jayawardene, averaging 99.21 before this match at the Galle International Stadium here, was the lone batsman to thwart the Indian spinners. He looked set to complete his 24th Test hundred before being caught behind off Kumble.
The teams observed a two-minute silence before the match in memory of former India batsman Ashok Mankad, who died in Mumbai on Friday.
Sri Lanka lead 1-0 in the three-match series following their win by an innings and 239 runs in the opening Test in Colombo.
