After Sri Lanka opted to bat, Lahiru Thirimanne (44) arrested a top-order slide while Angelo Mathews (40) played a lovely cameo as the islanders posted 160 for six against the defending champions.
Under the Duckworth/Lewis method, Sri Lanka were ahead by 27 runs when the heavens opened up. West Indies were struggling at 80 for four, needing another 81 runs in just 37 balls to win the match.