David Leggat: Must-wins now for Black Caps

Ross Taylor scored 62 off 37, including four fours and three sixes. Photo / AP

Dale Steyn chose a bad time - from New Zealand's perspective - to once more present his credentials as the world's best fast bowler in Chittagong.

Mitchell Johnson has had a purple run of form over the summer for Australia. But for sustained excellence over a period of years, hostility and as the guy you'd always want to be able to turn to in a squeeze, the flinty-eyed South African is your man.

He took away a game New Zealand should have won, even though no team has successfully chased down 170 or more in a T20 against South Africa.

Not only did Steyn take four for 17, his best in the world T20s, but he produced 16 dot balls out of 24 delivered.

Five of those were in the gripping last over, from which New Zealand needed seven, but which produced three wickets. His was a special performance.

The two-run defeat leaves New Zealand in precisely the position they would not have wanted to be in. They'll beat the Netherlands on Saturday night in their third pool game - if they don't, after the Dutch capitulated for a world record low 39 against Sri Lanka today, it's time to turn to table tennis - which leaves the Sri Lankans early on Tuesday as the clutch game.

New Zealand will want to belt the Netherlands to help run rate, which might yet be crucial.

At present they have a superior rate to both South Africa and England. Sri Lanka against England early on Friday now looms as critical to the outcome of the group.

Had New Zealand seen off South Africa, they would have all but locked in a semifinal spot. Sri Lanka are among the favourites, and for good reason.

New Zealand needed 31 off the last four overs, with seven wickets in hand and Ross Taylor well set.

However Colin Munro, Luke Ronchi, Corey Anderson, Luke Ronchi and Nathan McCullum, all well versed in these situations, were unable to help Taylor get the job done. For all Steyn's late-innings excellence, South Africa should not have been let off the hook. These are scenarios New Zealand have prepared for.

Taylor's 62 off 37 balls - including his fastest 50 off 26 balls - was another example of his damaging capabilities, however perhaps the most eye-catching batting effort came from Kane Williamson.

When he was slated as the first choice opener, brows were furrowed. He did not seem a natural fit for the role.

However he outsped the regular limited-overs opener Martin Guptill and his 51 off 35 balls was a top class effort - being dropped by bowler Imran Tahir on 36 notwithstanding.

JP Duminy saved the day for South Africa with his thrilling unbeaten 86 off 43 balls.
Indeed, captain Brendon McCullum might have rued his decision to give Williamson's offspin one over, which went for 13, at a point when Duminy was flying.

Kyle Mills and Nathan McCullum caught the eye with the ball, McCullum claiming his 50th T20 wicket when he bowled AB de Villiers.

So do New Zealand tinker for the Dutch game or stick with what they clearly feel is their best XI? They may not learn much out of the contest; then again ensuring those not needed so far have some match readiness for later in the tournament, should they be required, might be no bad thing.