Sri Lanka’s total of 182-6 gave them something to defend but, on a pitch made for batting, they were left to rue scoring only three from Matt Henry’s final over. That restricted the tourists to a score some way short of what they might have expected when Kusal Mendis guided them to 122-1 in the 14th over.
After being sent in for the third straight game, Mendis made Daryl Mitchell pay for spilling a catch at slip when he was on 10.
It was part of a streaky start from Sri Lanka that, with the ball swinging, saw them narrowly evade fielders on numerous occasions. But consecutive sixes from Mendis to end the fifth over got him going as the tourists ended the powerplay on 48-0.
Ish Sodhi made the breakthrough in the 10th over as Pathum Nissanka finally picked out a fielder, though this time he was unfortunate that Jimmy Neesham managed to snare an excellent diving catch.
Mendis took his side to 78-1 at the halfway mark and registered his half-century with the fourth of five sixes, before Ben Lister deceived the opener with a slower delivery to dismiss him for 73 from 48.
Still well place on 133-2 with five overs to bat, any plans for a big finish were hindered when Adam Milne ran out Kusal Perera with an impressive direct hit at long on.
Lister (2-37) earned a second with the slower ball before Henry tightened the clamps with a superb 20th over, setting up another runout while ceding only two byes.
Sri Lanka’s frustrations would have enhanced when Seifert started swinging. He did get a little lucky in the sixth over, as sub fielder Nuwanidu Fernando made a mess a mess of a tough chance, but in large it was a continuation of the clean hitting he displayed in Dunedin.
Chad Bowes, dropped on one in the first over, initially did well to feed the strike to his partner before sending a top edge sky high, a manner of dismissal becoming too familiar.
After the Black Caps ended the powerplay on 58-1, Seifert celebrated the quickest half-century of his career, coming from 26 balls. His timing was exemplary in scoring to all parts of the field, finding the fence with innovation as New Zealand reached 95-1 in 10 overs.
Tom Latham (31 off 23) was an effective partner in an 84-run stand before falling in the 15th over, leaving his side needing 43 from the final five. Seifert soon surpassed his previous best of 84, but with the target and a possible century is sight, he slapped a slower ball from Pramod Madushan to cover.
Nerves crept in during an 18th over from Kasun Rajitha that brought six runs and a 19th from Madushan that ceded seven. Mark Chapman’s booming six to begin Kumara’s closing over had the hosts within sight, but the next three deliveries saw him fall, Neesham run out and Mitchell dismissed.
Fortunately for New Zealand, Ravindra remained cool on the only delivery he faced, sealing a third straight series win ahead of this month’s tour of Pakistan.