"I think we read the game quite well today and the fielders backed us up. The fielding was outstanding. It creates really good pressure."
Earlier, on a sun drenched day, the Black Caps made 294 in front of 6942 fans.
After Sri Lanka nicked out opener Tom Latham for a duck in the opening over, local hero Kane Williamson walked to the crease to a rousing reception.
And the Black Caps captain did not disappoint with a typically classy innings full of supreme drives and audacious pull shots.
He was dismissed for 61 off 72 deliveries to end a stand of 122 with Martin Guptill.
Guptill and Ross Taylor put on a typically aggressive partnership of 81 before Guptil was out for 102, including three sixes.
Taylor looked good making 61 but the innings stuttered somewhat towards the end until Mitchell Santner hit two sixes off the last over.
Sri Lanka got off to a poor start, losing experienced danger man Tilikaratne Dilshan in the third over, caught behind off Trent Boult. The Tauranga left armer was rested for the previous matches against Sri Lanka and looked to have benefited from the break.
Sri Lanka were wobbling at 33/3. Adam Milne thrilled the crowd with the fastest spell of bowling yet seen at Bay Oval, letting one thunderbolt go at 150km/h.
Dinesh Chandimal and captain Angelo Mathews showed plenty of grit in a partnership of 93.
Mathews went past 4000 international ODI runs before Chandimal was out for 50, caught Williamson, bowled Boult.
The match was evenly poised with Sri Lanka five wickets down going into the final 10 overs. The pivotal moment came when Mathews was expertly caught on the boundary by Henry Nichols for 95 to give Henry his fourth wicket. Three balls later he had his fifth as Sri Lanka slumped to 253/9 and Boult came back to snare the final wicket.
The two teams meet again at Bay Oval in a Twenty20 international from 3pm tomorrow.