Shikhar Dhawan blasted his 11th century with a 132-run knock which came off just 90 balls and shared a 197-run stand for the second wicket with Virat Kohli, who chipped in with a valuable 82*-run as India easily chased down the target in just 28.5 overs.
Sri Lanka after losing the toss invited to bat enjoyed its best starts in early overs but suffered a batting collapse to be all out for 216 in 43.2 overs, losing nine wickets for just 77 runs.
Left arm spinner Axar Patel was the stand out bowler for India with career-best figures of three for 34 runs.
Chasing the target 217, India did not make the best of starts as Rohit Sharma (4) was run out in the fifth over.
Then later Shikar Dhawan punished the bowlers with 21 boundaries, including 3 sixes, finishing the match in style. He brought up his 11th ODI hundred off only 71 balls and it was the second quickest hundred against Sri Lanka by an Indian batsman after Sehwag.
The left-hander raised an unbeaten 197-run partnership for the second wicket with skipper Virat Kohli, who scored 82 off 70 balls.
The contribution by these two batsmen helped India to thrash Sri Lanka by nine wickets to take a 1-0 lead in the five-match series.