A cracking half-century by Brendon McCullum set New Zealand up for a comfortable three-wicket win over Sri Lanka in their first one-day international in Christchurch Sunday.

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After McCullum's 51 in 19 balls had provided his side a comfortable target well under four an over, Corey Anderson stepped up with 81 to ensure the job was done.

When Anderson was dismissed New Zealand required a further 10 runs which they achieved with seven overs remaining.

Sri Lanka, electing to bat first, posted 218-9 on the back of Mahela Jayawardene's 104 in 107 balls.

It was the 18th ODI century for the 37-year-old, the fifth highest run-scorer in the history of the shortened game, who was rarely in trouble by the New Zealand attack until caught in a wicket meltdown late in the late innings.

Although Jayawardene received little support in the middle, Sri Lanka had reason to believe their modest target was defendable when they removed Martin Guptill on the third ball of New Zealand's reply.

But for McCullum that was a signal to open up as he blazed away to bring up his 50 in just 19 deliveries with six fours and three sixes.

It was the seventh fastest half century of all time, and only two behind the record held by Sri Lankan Sanath Jayasuriya, who took 17 balls to reach 50 against Pakistan in 1996.

The second game in the seven-match series is in Hamilton next Thursday.