New Zealand 159 for 4 (Young 86*, Nicholls 44*) beat Sri Lanka 157 (Nissanka 57, Henry 3-14, Mitchell 3-32, Shipley 3-32) by six wickets
New Zealand's seamers triggered a second successive Sri Lanka collapse, sending the visitors sprawling in the first few overs, before they eventually sputtered to 157 all out. Then, despite an early wobble of their own, New Zealand strode confidently to the target, inside 33 overs, to wrap up the series 2-0.
This is Sri Lanka's fifth consecutive loss (in completed matches), and their seventh loss in eight games, and as such, it confirms that they have not qualified for this year's World Cup directly. They will instead have to play the qualifying series in Zimbabwe in the middle of the year to earn their place. New Zealand, meanwhile, have cemented their position atop the ODI Super League table, with 175 points.
But then, the likes of Charith Asalanka and Dhananjaya de Silva also fell against the bowling of allrounder Mitchell, both attempting legside strokes, while failing to account for the extra bounce in the surface. Asalanka was caught at deep midwicket, and de Silva's leading edge settled in the hands of mid off. At their demise, Sri Lanka were 70 for 5 in the 19th over.
Soon after he got to his fifth career half-century off 58 balls, but then was out next over in Sri Lanka's most wasteful dismissal. Having set off for a quick single towards cover, Nissanka changed his mind and attempted to send non-striker Shanaka back to his crease. Shanaka kept coming, however, and Nissanka had no hope of making his ground, having paused.
Although Sri Lanka's lower middle order resisted briefly through Shanaka, who made 31, and Chamika Karunaratne, who hit 24, they could put together sufficiently substantial innings. Sri Lanka were all out inside 42 overs.
Having come to the crease in the second over, Young was largely watchful through the powerplay, hitting only three genuinely poor deliveries to the boundary, as he moved to 20 off 36 while the fielding restrictions were in operation. He seemed settled through the early middle overs, even as Tom Latham fell, leaving New Zealand 59 for 4, and Sri Lanka with a small window of opportunity.
Young and Nicholls eventually settled into a rhythm of collecting risk-free runs into the outfield, although there were nervous moments at the start of their partnership. One pull shot from Young, off the bowling of Kumara, landed only a little way short of the deep fielder; Nicholls was given out lbw on 1, but reviewed successfully.
Eventually, batting got easier, and New Zealand were loping to their target, both batters finding boundaries around the ground. Young got to his half-century - the third time he's crossed this milestone, with the other two trips to 50 having brought centuries - off the 71st delivery he faced, easing Lahiru Kumara to the straight boundary. The pair brought up their century stand with the last hit of the game.
From Sri Lanka's bowlers, Lahiru Kumara had been the most intense, taking the wicket of Chad Bowes with his first delivery, then dismissing Tom Blundell in that same over, both batters nicking to the wicketkeeper. When Kasun Rajitha also had Mitchell edging in the seventh over, they had New Zealand at 21 for 3.
But thanks to Young, the hosts saw through that tough period.
Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @afidelf