New Zealand cannot lose the six-match series

New Zealand beat South Africa by six wickets in Dunedin for an unassailable 3-1 lead in the one-day series.

Chasing 260 to win, the Black Caps got home with an over to spare after a 126-run stand between Hamish Marshall (74) and Scott Styris (69).

Chris Cairns smashed Makhaya Ntini for 12 off the 49th over, with six from the last ball, to complete the job.

Jacques Rudolph had led the way with 70, and Nicky Boje hit a half-century, in the tourists' total of 259-7.

I really think we've given it all and we've been out-performed Graeme Smith More reaction

The fourth match in the series of six contests began a day late following bad weather in Carisbrook and the toss was won by the home side.

Matt Mason, replacing the injured Daryl Tuffey, made an early impression when he trapped Herschelle Gibbs lbw for 16 and then Jacob Oram removed the dangerous pair of Jacques Kallis (13) and Grame Smith (37).

By the time Boeta Dippenaar had been bowled by Chris Cairns for a laborious 18 off 44 balls, the score was 110-4 and more than half the overs had been used.

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But Boje, Rudolph and Mark Boucher (35 off 28 balls) all scored their runs quickly to set New Zealand a challenging total. Oram finished with 3-51.

Black Caps openers Stephen Fleming (51) and Michael Papps (29) got the team off to a good reply in a partnership of 71 for the first wicket before Marshall and Styris stamped their authority on the game in a thrilling stand of 126 at better than a run-a-ball.

South African seamers Andre Nel and Makhaya Ntini were once again unable to control their direction sufficiently to avoid being severely punished.

Shaun Pollock, unexpectedly passed fit to play in the game, was his economical self but finished wicketless in his 10 overs.

New Zealand: Stephen Fleming (captain), Michael Papps, Hamish Marshall, Scott Styris, Craig McMillan, Chris Cairns, Jacob Oram, Brendon McCullum, Daniel Vettori, Kyle Mills, Michael Mason.

South Africa: Graeme Smith (captain), Herschelle Gibbs, Jacques Kallis, Boeta Dippenaar, Jacques Rudolph, Mark Boucher, Lance Klusener, Nicky Boje, Albie Morkel, Makhaya Ntini, Andre Nel.