Kane Williamson's fifth one-day international century and a late Luke Ronchi onslaught set up New Zealand to beat Sri Lanka by four wickets in Nelson and edge ahead again in the seven-match series.
After New Zealand's victory in Christchurch, Sri Lanka's winning response in Hamilton and the washed-away contest in Auckland, a gripping finish looked in store at the Saxton Oval.
But Ronchi went on the attack just as New Zealand looked to have run into problems, and saw the home side over the line by cracking 32 not out from 15 balls.
Sri Lanka had posted 276 all out, falling three deliveries short of batting out their allotted 50 overs, with Mahela Jayawardene flaying the home attack for 94 from 82 balls and Kumar Sangakkara weighing in with a snappy 76.
Sangakkara and Angelo Mathews fell to successive deliveries from Adam Milne in the 34th over, with Sri Lanka slipping to 180 for four.
Although they were 245 without further loss in the 45th over, the tourists did not press on, as they may have been expected to, to pass 300.
The lower order had contributed little but there was hope for Sri Lanka when New Zealand dangerman Brendon McCullum perished early in the reply.
He made just 11 before being first man out in the fifth over, Thisara Perera snaffling the chance at mid-on to give Nuwan Kulasekara a prized wicket.
Martin Guptill and Ross Taylor both departed without reaching full flow, and New Zealand were toiling on 63 for three in the 16th over, but Williamson put on 88 for the fourth wicket with Grant Elliott - who scored half of those runs - and 79 with Corey Anderson.
Williamson fell to the final ball of the 44th over, bowled by Perera for 103 with New Zealand still 47 runs short of their target.
Anderson was run out by Tillakaratne Dilshan for 47, and a tight finish looked inevitable, but Ronchi had other thoughts and clubbed three sixes in his thrilling but brief innings.
Former New Zealand skipper Daniel Vettori finished the job by reaching the ropes with the first ball of the 49th over.