The Black Caps' three run-scoring machines

Martin Guptill leaves the filed after scoring his fourth century on 2015. Photo / AP

The runs keep flowing for New Zealand's brilliant one day batsmen with Martin Guptill joining Ross Taylor as the only Kiwis to score four centuries in a calendar year.

Guptill steered New Zealand to victory in Potchefstroom to level the series with South Africa, continuing a fine season for the Aucklander who had gone in to the World Cup with questions over his form.

Williamson and Taylor are still well short of the remarkable record set by Sachin Tendulkar, who hit nine centuries from 34 games in 1998. And New Zealand's position as the one day batting kings is inflated because they have played far more matches than any other nation this year.

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But it is still an impressive sight, with Williamson, Guptill and Taylor atop the scoring list. They are the only players, along with Sri Lanka's Tillakaratne Dilshan, to have scored more than 1000 runs.

Guptill praised his young opening partner Tom Latham for setting New Zealand on the right track in the eight wicket victory over South Africa.

Guptill said: "I do like playing here (in South Africa) because you are confronted with a lot of different conditions.

"It was a struggle the way the pitch played and Tom really got us underway - we could cruise from there.

"We've got five top line players rested or injured and it shows the depth we've got - it's good for the future."

Guptill recalled his slow start to the year, going into the World Cup with just two 50s under the belt. Apart from the disappointment of New Zealand's World Cup final capitulation, it has been a stellar year for Guptill, who is one of those players who seems to fall out of favour with the public so easily.

While the overall numbers paint the retiring Sri Lankan superstar Kumar Sangakkara and South Africa's AB de Villiers as the top one day batsmen, it has still been an excellent year for a crop of Kiwis which also includes Grant Elliott and Brendon McCullum.

Williamson tops the world list with 1278 runs at an average of 58. Guptill is one run back and is averaging 53 this year from 28 innings, the most among any of the leading run scorers. Taylor has 1041 runs from 24 innings, at an average of 61. Sangakkara has averaged 86 from 14 innings this year while de Villiers has not only scored heavily but has done so at an exceptional 140 strike rate.