Streak clubbed an unbeaten 72 (Getty Images).

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Nathan Astle struck an unbeaten century as New Zealand cantered to a six-wicket win in their crucial World Cup Super Six clash against Zimbabwe on Saturday.

Needing to win to keep any realistic hopes of reaching the semi-finals alive, New Zealand eased to victory on the back of Astle's unflustered 102 not out.

Astle rarely looked in trouble during a 122-ball knock which included 11 fours and also saw him share in a decisive 121-run stand with Chris Cairns.

Cairns weighed in with 54 to help lay the foundation for victory after captain Stephen Fleming had got the innings off to a fine start with a fluent 46.

Zimbabwe, without leg-spinner Brian Murphy who tore a calf muscle practising between innings, enjoyed only limited success after Doug Hondo claimed the early wicket of Craig McMillan.

Fleming looked in fine form - but his dismissal lbw to Andy Blignaut, followed soon afterwards by the all-rounder's removal of Scott Styris, offered hope.

Yet other than Sean Ervine bowling Cairns the ball after he had moved to his half-century with a six, chances for Zimbabwe to make further inroads were few and far between.

Their disciplined bowling and fielding prevented the Kiwis from running away with victory - but with wickets in hand, their run-a-ball target was never likely to cause too many problems in the final 10 overs.

That Zimbabwe had set a testing total at all was due almost entirely to the gritty batting of Tatenda Taibu and captain Heath Streak. The pair came together with their side struggling on 106 for six but shared in a painstaking 68-run partnership to lay the platform for a late flurry.

Taibu hit a dogged 53 before being trapped lbw by Chris Harris attempting to flip the ball over wicketkeeper Brendon McCullum's head.

Streak, however, picked up the attack and went to his half-century with two sixes in a Harris over which went for 23. He finished 72 not out.

Sean Ervine also joined in the late fun, cracking an unbeaten 31 from just 14 deliveries as 62 came from the final three overs.

The Kiwis had earlier wrested back control after a second-wicket partnership of 54 between Craig Wishart and Andy Flower had got Zimbabwe off to a solid start.

Cairns sparked a mini-collapse with the first of three Zimbabwe wickets for six runs which saw Wishart depart after well constructed 30 and Grant Flower and Guy Whittall follow in quick succession.

Andy Flower looked to repair the damage but took on Astle's arm and became the first of two run-out victims after a promising 37. Andy Blignaut also went run out following a similarly sharp piece of work by McCullum.