Chasing a challenging target of 227, Sri Lanka had a disastrous start with both their openers falling cheaply. Seasoned Tillakratne Dilshan was bowled by Corey Anderson for a duck while Dinesh Chandimal too went back to the pavilion after being cleaned up by Adam Milne.
Lahiru Thirammane and Chamara Kapugedara then rallied the innings with a 66 runs stand off 41 balls before the former was caught by Anderson off Ish Sodhi in the 13th over.
But Sri Lanka were never in the fray as they kept on losing wickets at regular intervals and ended at 152 for seven.
The Kiwis started on a bad note as their skipper Kane Williamson, after being dropped on a duck in the very first over, fell cheaply for just 10 with only 16 on the board.
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Another Kiwi opener Martin Guptill hit seven fours and a six in 41 runs quick knock off 25 deliveries before being caught at cover by Senanayake.
Munro then stitched a partnership with Anderson as they added 92 for the third wicket.
Brief Scores: New Zealand 226/5 in 20 overs (Colin Munro 67, Corry Anderson 60; D Shanaka 2/48).
Sri Lanka 152/7 in 20 overs (L Thirummane 41, C Kapudegadara 38; Adam Milne 3/26 and Ish Sodhi 2-19).