Chasing a target of 233, Man-of-the-Match Hope scored 110 and Lewis featured in an opening stand of 143, a record-opening stand for the West Indies against Sri Lanka in the West Indies, which was ended when the latter was bowled by an in-swinging yorker from Dushmantha Chameera for 65.
Lewis had faced 90 balls in his 109-minute stay at the crease hitting four fours and two sixes.
Hope, who dropped from the West Indies Test squad last year for loss of form, was a picture of composure, facing 136 balls from which he hit 12 fours and a six in his 10th ODI century before he, too, was bowled by Dushmantha Chameera who finished with 2-50 from his 10 overs.
Hope also shared in a 72-run second-wicket stand with Darren Bravo who hit two fours and a six and in his unbeaten on 37 at the end. With him was Jason Mohammed, who was not out on 13.
Sri Lanka would have been disappointed after winning the toss and opting to take first strike, were given a solid platform of 105.
The partnership was broken two balls into the 20th over by Kieron Pollard, who brilliantly caught Dimuth Karunaratne off his own bowling for 52. He had faced 61 balls and struck four fours in his 89 minutes at the crease.
Eleven balls later it was 112 for 2 when Danushka Gunathilaka, who was going well on 55 when he was controversially given out for obstructing the field, ending his 98-minute stay at the crease during which he struck seven fours from the 61 balls he faced.
The incident seemed to rattle Sri Lanka as two run-outs (Pathum Nissanka and Angelo Matthews) followed that saw Sri Lanka slide to 126 for 4.
Ashen Bandara scored the third half-century of the Sri Lankan innings that provided some stability to the lower order but by then the run rate had fallen before five runs and over and he was without a partner who could successfully take on the West Indies bowling attack.
His was the ninth wicket to fall in the 48th over bowled by Jason Holder for an even 50 that included four fours.
Holder, who also accounted for the wicket of Chameera returned figures of 2-39. Jason Mohammed, who was introduced into the attack late had 2-12 from his four overs having claimed the wickets of Kamindu Mendis and Wanindu Hasaranga de Silva.
There was a wicket each for Alzarri Joseph, Pollard and Fabian Allen, in a performance of which Coach Phil Simmons would be proud.
