Mahela Jayawardene led from the front with 65 not out as the hosts chased down 130 in 15.2 overs to notch up their second successive win in the Super Eights.
Pallekele: Sri Lanka became a firm favorite to qualify for the World Twenty20 semifinals after crushing West Indies by nine wickets in the Super Eights on Saturday.
Sri Lanka can advance with a win or narrow loss — because of an excellent net run rate — to defending champions England on Monday.
West Indies need to beat New Zealand on the same day and then wait for the outcome of the Sri Lanka-England match to qualify.
Captain Mahela Jayawardene smashed an unbeaten 65 off 49 balls in Sri Lanka's successful chase, reaching 130 for 1 with 28 balls to spare after West Indies was buckled down for 129 for 4.
Jayawardene shared a 108-run unbroken stand with Kumar Sangakkara (39) off 75 balls after Ravi Rampaul had Tillakaratne Dilshan (13) caught behind in the third over.
Both batsmen batted comortably at Pallekele International Stadium and gave respect to only offspinner Sunil Narine, who gave away 23 runs but remained wicketless.
Jaywardene hit 10 fours and a six in his unbeaten knock while Sangakkara faced 34 balls and hit five boundaries.
Earlier, Sri Lanka finger spinner Ajantha Mendis bowled a miserly spell of 2 for 12 to help restrict West Indies.
Marlon Samuels top-scored with 50 off 35 balls with four boundaries and two sixes and shared the best stand of 65 for the third wicket with Dwayne Bravo, who made 40.
Mendis had opening batsman Charles Johnson (12) stumped in the fifth over and returned to clean bowl Kieron Pollard (1).
Seamer Nuwan Kulasekara added to West Indies' early problems when, two balls after Johnson departed, hard-hitting Chris Gayle was out for 2 playing a loose shot off a slow delivery. Gayle had struggled for nine balls against the change of pace by the seamers.
Jaywardene — who lost the toss — never allowed the opening pair of Charles and Gayle to free their arms as they did against England in the 15-run win on Thursday.
Jayawardene intelligently used four bowlers within the first six overs of the batting powerplay and was duly rewarded with the wickets of both openers.
Samuels and Bravo revived the innings, but never looked to threaten to score boundaries at will as Jayawardene rotated his bowlers effectively.
Dilshan took well-judged catches of both batsmen in the deep as West Indies tried to break the stranglehold.
The only bright moment in West Inides' knock came in the 17th over when Andre Russell (19 not out) and Samuels hit Kulasekara for two sixes and two fours.
Sri Lanka were forced to leave out Akila Dananjaya after the 18-year-old offspinner broke his left cheekbone while trying for a caught-and-bowled during a thrilling victory in the one-over eliminator against New Zealand.
West Indies recalled fast bowler Fidel Edwards and left out spinner Samuels Badree.