With the fixture continuously interrupted by inclement weather and forced into a reserve day following a heavy downpour on Sunday, the West Indies now face a challenging victory target of 230 based on the Duckworth/Lewis Scoring Method in a match reduced to 41 overs-per-side.
Sangakkara, who resumed on the additional day in partnership with fellow left-hander Lahiru Thirimanne, extended the fourth-wicket partnership to 69 when play eventually got under way 105 minutes late because of more rain, resulting in the match being reduced to 45 overs-per-side at that point.
Thirimanne was bowled by Marlon Samuels for 23, after which another light shower drove the players off the field briefly, necessitating a second reduction in the number of overs.
All the while, Sangakkara stayed focused on the task at hand, playing with his trademark fluency and growing in confidence and a sense of adventure, especially when joined by captain Angelo Mathews. The powerful all-rounder blazed 30 off 27 deliveries and gave the innings important impetus while also taking the pressure off the senior batsman.
When Mathews fell, caught by Devon Smith off Kemar Roach, Sangakkara stepped up a gear, taking considerably more risks and capitalising on more wayward and indisciplined West Indies bowling.
A total of 31 extras contributed generously towards the Sri Lankan effort, a tally that included 24 wides and three no-balls. Roach was the most successful of the bowlers with four for 27 although Darren Sammy's medium-pace was the most economical, his nine overs costing just 24 runs.
Sangakkara's 95-ball knock, his 76th half-century in one-day international cricket, included one six and six fours but was defined more by trademark timing, placement and a sensible appreciation of the circumstances than the hell-for-leather hitting usually associated with the final stages of a limited-over match.