Dhoni-less India are bowled out for 187 chasing 349 for victory as Sri Lanka's opening batsmen score centuries.
Praise for Tharanga, Jayawardene as Sri Lanka thrash Kohli's India
Tharanga was unbeaten on 174 off 159 deliveries – the highest individual score in one-day internationals in the Caribbean – while Jayawardene scored a near run-a-ball 107 for a stand of 213 in Sri Lanka's shuddering total of 348 for one.
In response, India were all out for 187, Ravindra Jadeja digging in for 49 with Rangana Herath taking three for 37.
Sri Lanka captain Angelo Mathews, who promoted himself to No 3 and raced to 44 off 29 balls said it was an important win in the larger context.
"We really needed this," said Mathews, who acknowledged that his team was under pressure to get a good result after being beaten comfortably by the West Indies in the tournament-opener last Friday. "Hats off to Mahela and Upul, who really set this up for us and allowed the bowlers to complete the job."
India's reply suffered an early blow when they lost Rohit Sharma for just five when he drilled the ball to Angelo Mathews at short midwicket off Nuwan Kulasekara's bowling.
They were nowhere near the run rate they needed to be and things got worse when they lost the wicket of Shikhar Dhawan when he was caught by Tharanga for 24.
It left India on 52 for two and heralded a mini-collapse.
With just five more runs on the board they lost captain Virat Kohli for two when his hook shot was caught by Lasith Malinga off the bowling of Mathews and eight runs later, Murali Vijay was bowled by Malinga for 30.
It left India floundering and they reached the halfway point 25 runs behind Sri Lanka at the corresponding stage of their innings.
However, the pendulum swung even further Sri Lanka's way when Dinesh Karthik became the fifth Indian batsman to go, stumped by Kumar Sangakkara for 22 to leave India on 118 for five.
There was a feeling of inevitability now with India not showing any urgency and it was surely all over as Suresh Raina was the sixth man out on 142 after making 33.
Raina and Jadeja went for a second run after an overthrow and with the former diving for home, his bat rose and with Mathews taking the bails off it was six down for India.
India lost two further wickets for no runs on 153, both coming off the bowling of Sachithra Senanayake.
Ravichandran Ashwin had made four when he tried a reverse sweep which got a top edge and found Malinga at short third man.
Shami Ahmed then went for a golden duck when he missed Senanayake's quicker delivery and it took out leg stump.
Ishant was next for two as Sangakkara made a sharp catch to his left and while Jadeja valiantly resisted, Sri Lanka soon crumbled.
"It was a bad day at the office," said stand-in captain Kohli. "We took some time to switch on in the field and by then the Sri Lankans were off and away, and even when we batted I don't think we applied ourselves as well as we should have."
Earlier India won the toss and chose to put Sri Lanka in to bat.
Sri Lanka made a steady start and Jayawardene brought up his 50 with a lofted shot over Jadeja.
Tharanga's fifth boundary took Sri Lanka within a run of the 100 mark which was reached with Jayawardene hitting Ashwin to long off.
Tharanga got to his 50 with a single off Ashwin.
Jayawardene hit a six over wide long off before India finally made the breakthrough with Ashwin's very next delivery, this time Umesh Yadav holding on as he dived to his right at short third man.
His innings of 107 had come off 112 deliveries and included nine fours and two sixes.
Mathews came to the crease and soon after Tharanga reached a hard-worked ton with a single off Shami Ahmed's overpitched delivery.
The pair both made India's attack look insipid, Tharanga finishing with 19 fours and three sixes while Mathews' quickfire innings of 44 off 29 balls included one six and four boundaries.
India, bottom of the standings after losing their opening two matches, now need to lift themselves immediately for the second half of the tournament in Trinidad.
They face a rematch against a buoyant West Indies side at Queen's Park Oval on Friday.
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