MANCHESTER: Former New Zealand captain Daniel Vettori has hailed Kane Williamson as New Zealand's greatest-ever one-day player after his match-winning World Cup century against South Africa.

Williamson made an unbeaten 106 to guide the Kiwis to a nervy four-wicket win with three balls to spare at Edgbaston on Wednesday as they maintained their unbeaten record.

With the Black Caps needing eight runs to win in the rain-hit 49-over-a-side game, Williamson smashed paceman Andile Phehlukwayo for six to bring up his 12th ODI century and hit the next ball for four to seal the victory.

"Kane Williamson has to be New Zealand's greatest ODI player of all time -- and innings like that against South Africa tell you exactly why," Vettori wrote in his column for the International Cricket Council.

"He's already there now and by the end of his career his record will far exceed anything we've had in the past or present, he really is that good."

New Zealand, the runners-up in 2015, were in trouble at 137 for five in the 33rd over before Colin de Grandhomme (60) joined skipper Williamson at the crease.

The pair put on 91 runs for the sixth wicket as Williamson paced his innings to perfection, hitting nine fours and a six in his 138-ball knock.

"Kane has done so much in such a short period, whether a captain or not, he's been exceptional and he's an absolute joy to watch," said Vettori.

"He plays all the shots, he knows how to manipulate the strike and he's always going to run hard.

"What differentiates him from a lot of batsmen in this day and age is his sole focus is winning the game and he tailors his batting towards that."

Williamson, who made his ODI debut against India in 2010, averages an impressive 47.36 in 143 matches.

New Zealand, who play the West Indies on Saturday, top the 10-team table in the World Cup round-robin phase, with four wins out of five matches. Their game against India was washed out. —AFP