New Zealand 175 for 5 (Taylor 48, de Grandhomme 44, Hasaranga 2-21, Malinga 2-23) beat Sri Lanka 174 for 4 (Mendis 79, Dickwella 33, Southee 2-20) by five wickets
A bruising 79-run fourth-wicket stand off 37 balls between Ross Taylor and Colin de Grandhomme energised a flailing New Zealand innings, and set them on track for what would eventually become a comfortable victory.
The visitors ran down Sri Lanka's 174 with three balls and five wickets remaining. The pair had come together with the score at 39 for 3, with the required rate climbing toward 11, but blasted four sixes and seven fours between them, as Sri Lanka's bowlers struggled to contend with a wet, slippery ball. The game was still not quite safe when the two were dismissed, but Mitchell Santner and Daryl Mitchell saw the visitors home with a 31-run stand that came off 16 balls.
New Zealand's victory was despite Sri Lanka having produced the best individual innings of the evening. Kusal Mendis had earlier struck 79 off 53 balls opening the innings, putting on a 63-run partnership with Niroshan Dickwella for the third wicket in the process. But some dawdling in the middle period, and some excellent bowling from Tim Southee at various stages of the innings, prevented Sri Lanka from posting a really big total.
Southee took 2 for 20, and was almost matched by Lasith Malinga, who struck the base of Colin Munro and de Grandhomme's middle stumps with searing Yorkers on his way to 2 for 23. Had he not flung five wides down the legside at the start of the 19th over, Sri Lanka might have had a chance in the final over. As it happened, New Zealand required only three to win off the 20th.
It hadn't taken long for either de Grandhomme or Taylor to begin finding the boundary. De Grandhomme clubbed his second ball for four past cover, and Taylor found his first four via the sweep - various iterations of the shot going on to prove fruitful for him through the evening - but it wasn't until the halfway mark in the innings that big blows began to come in quick succession. New Zealand made 17 runs off each of the 11th, 12th and 13th overs, the pair hitting four sixes and two fours through this period, in addition to running well between the wickets.
It could have gone wrong, though. Sri Lanka would rue the dropped catch off Taylor on 31 - attempting a third six off Akila Dananjaya, Taylor miscued one to deep midwicket, but Dasun Shanaka could not hold on to a straightforward chance.
De Grandhomme was out for 44 off 28 in the 14th over, but Taylor carried on until the 17th, before being trapped lbw by Wanindu Hasaranga after 48 off 29 balls. A six apiece from Santner and Mitchell, plus those five Malinga wides, ensured New Zealand's dominance at the finish.
In Sri Lanka's innings, Mendis' opening stand with Kusal Perera had been rapid - 41 runs coming off 4.3 overs - but Avishka Fernando's inability to find the gaps or the boundary helped sap momentum from the innings, as Mendis himself entered a quieter phase of batting with the spinners in operation. Fernando was eventually dismissed for 10 off 17 - the pair going at just under a run-a-ball through the course of their 28-ball association.
Sri Lanka's run rate recovered during Mendis' next partnership - Dickwella making 33 off 25, before Southee had Mendis caught superbly at long-on by Martin Guptill. Between them, Shanaka and Isuru Udana hit three sixes in the final over, and seemed to have raised themselves to a competitive score. But their bowlers were rattled by that Taylor-de Grandhomme stand, and the spinners in particular could not find the turn that would have envenomed them, as they struggled to grip a wet ball.
New Zealand go 1-0 up in the series. The second match of three is on Tuesday.
Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @afidelf