New Zealand's new-ball attack against West Indies' flimsy top order; whether Brendon McCullum is removed early; the ability to counter the dual threat of Daniel Vettori's economy and strike-rate. Numerous aspects could decide the Wellington quarter-final, but if West Indies are able to lay a platform the contest between their hefty strikers in the middle order and New Zealand's death-bowling tactics shapes as vital.

McCullum only knows one way to play. In the field it is an all-out search for wickets. Whereas every other captain juggles his bowlers with the closing overs firmly in mind, McCullum's main aim is to make them irrelevant. When it works, as it did dramatically against England and Australia in recent weeks, it looks like genius.

However, the flip side was evident against Bangladesh when, through a combination of a poor day for Mitchell McClenaghan and a desire to take wickets, Grant Elliott was required to bowl two of the final three overs. Bangladesh rattled off 104 from the last 10 overs, but New Zealand had just enough in the tank to overhaul them. If the death bowling is off against West Indies, the likes of Darren Sammy and Andre Russell could cause horrendous damage.

"If we can get a good start, blunt the attack early, then we could be in for a good ball game," Curtly Ambrose, West Indies' bowling coach, said in a slightly more toned-down version of Sammy's comments on Wednesday when he said New Zealand "didn't have an answer" in the closing overs against Bangladesh.

McCullum, though, is unlikely to change his plans. In fact, as Sri Lanka showed in the first quarter-final by promoting Kusal Perera, switching tactics last-minute before a key game can do more harm than good. Adam Milne is set to return in place of McClenaghan and if all goes to script for McCullum he will not look beyond his five main bowlers, but should a sixth be required Elliott will again be the man under pressure.

"I've done it for Wellington and throughout by career, you mix and match some overs where you can," Elliott said. "With T20 you are under the pump all the time so you have to develop the skills to curb the runs as much as you can.

"Whenever Baz [McCullum] calls on me I enjoy it. It complements my batting game. I certainly pay more attention in the field when I'm bowling. Generally if I am bowling we aren't doing too well as a unit so if we continue the way we have gone then I shouldn't need to bowl too many."

Death bowling has been under the microscope throughout this tournament. Teams have attempted to stack wickets in order to unleash from the 35th over onward, which is both the justification and danger of McCullum's approach, and some heartache has been handed out to bowlers. The current era of one-day bowlers are having to combat batsmen with a wider array of strokes than ever before - AB de Villiers and Glenn Maxwell being two of the best examples of players who score 360 degrees - but there remains scepticism from previous generations about the extensive use of variations.

"I'm astounded because if you look at the last 10 overs of teams batting, particularly batting first, 110, 120, 130 runs are being conceded," Richard Hadlee said while sat alongside fellow knight Ambrose. "You look at the way bowlers are bowling and there just aren't the yorkers. I know that with yorkers if you don't get it right, they'll go out of the park like anything else but there's a tendency to bowl back of a length, to bowl the slow bouncer, other different changes of pace, to bowl full and wide as another way.

"These are tactics and the way the modern game is but I've always thought that if you get the yorker right, it's pretty difficult to hit that out of the park."

Ambrose, meanwhile, spoke with two hats on. As part of the West Indies backroom staff he will delight if New Zealand's attack is under the pump on Saturday, but as part of the bowlers' union he does not believe the game is an even contest anymore.

His charges have certainly come in for some punishment in this tournament, most staggeringly when Jason Holder went from having figures of 5-2-9-1 against South Africa to 10-2-104-2 at the hands of de Villiers.

"I think presently it's grossly one-sided. Everything favours the batsman," he said. "It's too one-sided and the powers that may be need to look at it seriously and make it a little more even because at the moment it's all about the batting. If you don't have bowlers you have no cricket. Soon we may have to get some bowling machines."

Hadlee, though, was a touch sanguine about the challenge for the bowlers. "A lot of teams are in trouble early on. They've lost 1 for 10, 2 for 20 and clearly the two balls that are used, one at each end, is having a dramatic effect. We're seeing some good contests early on but after teams rebuild and get to a competitive total so the balance to me is good at the moment."