Opener Lahiru Thirimanne hit 102 off 110 balls as Sri Lanka piled up 6-296 after electing to bat in the opening match of the Asia Cup one-day tournament against Pakistan in Fatullah on Tuesday.
The left-hander's second one-day century led Sri Lanka's charge in which Kumar Sangakkara made 67 and skipper Angelo Mathews remained unbeaten on 55 off 50 balls.
Sri Lanka were coasting at 2-204 in the 36th over when Pakistan slowed the pace by grabbing four wickets in the space of nine overs.
Leg-spinner Shahid Afridi and seamer Umar Gul claimed two wickets each, but Pakistan still face a stiff target of six runs an over to win the day-night match.
Thirimanne and Sangakkara compiled Sri Lanka's highest second-wicket stand against Pakistan, adding 161 after Kusal Perera had fallen in the eighth over for 14.
Thirimanne, promoted to open the innings in the absence of the injured Tillakaratne Dilshan, hit 11 fours and a six before he was bowled by Saeed Ajmal in the 36th over.
Sangakkara continued the awesome batting form he showed during the preceding bilateral tour of Bangladesh where he scored 319 and 105 in the second Test in Chittagong and 128 in the second one-dayer in Dhaka.
The left-hander hit eight boundaries for his 84th one-day half-century when he gifted away his wicket, pulling a short ball from Gul to Ahmed Shehzad at mid-wicket.
Sri Lanka, who were without the injured trio of Dilshan, seamer Nuwan Kulasekara and spinner Rangana Herath, handed an international debut to all-rounder Chaturanga de Silva.
India, Bangladesh and Afghanistan are the other teams in the tournament which decides the regional champion in one-day cricket.
