Two days after routing their visitors by 108 runs in Dunedin, New Zealand posted a 120-run victory at the same University Oval ground to move 4-1 ahead and again showcase their World Cup threat.
Kane Williamson and Ross Taylor narrowly missed out on centuries but could rest safe in the knowledge their scores of 97 and 96 respectively batted Sri Lanka out of the game.
All-rounder Corey Anderson rattled off a rapid 40, and Sri Lanka offered little in reply other than Kumar Sangakkara’s defiant 81.
They folded from 146 for three to 195 all out, a tepid response to New Zealand’s 315 for eight.
Anderson took man-of-the-match honours after following up his 28-ball batting cameo with bowling figures of four for 52, removing top-order men Tillakaratne Dilshan, Mahela Jayawardene and Dimuth Karunaratne before pinning Thisara Perera lbw later in the innings.
Perera had early been ruinously expensive with the ball, his 10 overs costing 86 runs and yielding just the wicket of opener Martin Guptill.
Sri Lanka fell into disarray in their desperate chase, with Dinesh Chandimal, Jeevan Mendis and Dhammika Prasad all run out, before Mitchell McClenaghan completed the win by having Suranga Lakmal caught off a top edge.
The match had been all but over from the point Sangakkara departed, eighth wicket down, caught by Daniel Vettori at mid on off the bowling of Trent Boult after cracking the previous two deliveries to the boundary.
Sri Lanka, World Cup runners-up four years ago, will head to Wellington for Thursday’s final match in the series, looking to show they still have such quality in their ranks, but New Zealand’s credentials are becoming clear ahead of the global tournament they will co-host with Australia from the middle of February.