If Mitchell Starc's performances are a barometer of Australia's World Cup prospects, then you might as well hand them the trophy here and now.

With his second five-wicket haul of the tournament - and his fourth of four or more - Starc marched past the 22 wickets in eight games with which he sealed his Player of the Tournament title in the 2015 campaign, and has moved to within three of overhauling the all-time record for a World Cup campaign, the 26 that Glenn McGrath claimed in another of Australia's five World Cup wins, in the Caribbean in 2007.

And yet Starc remains unmoved by the prospect of individual milestones. Asked what it would mean to overhaul the great McGrath, he replied: "Not much if we don't win the World Cup." With every passing performance, the odds on that turn of events lengthen.

For New Zealand, there was a bleak inevitability to Starc's interventions at Lord's. His first spell may have been wicketless but it came against a pair of openers whose only instinct was survival - and seeing as he chipped in with a 96mph thunderbolt in his third over, it seemed from the sidelines to be a prudent course of action.

WATCH on Hotstar (India only): Starc dazzles with a five-for

But with his team-mates keeping up those restrictive methods, Starc was able to return with a vengeance for his latter spells. Recalled for the 26th over, just as New Zealand had started to realise that discretion means little without a touch of valour, he struck with his fourth ball to dislodge the main man, Kane Williamson.

Ten overs later, he repeated the trick - this time sinking Tom Latham at midwicket - and with four overs still up his sleeve, there was now no reason not to keep him going in search of a clean kill. By attacking the stumps with lethal pace and late swing as a bonus, he once again displayed a method that, so far, only India's star-studded batting has managed to counter.

"[Attacking the stumps] is part of my game-plan," said Starc. "Again, it was a worn wicket today, so we were all fortunate that Finchie won the toss and we got to bat first. I believe they bowled well at the start. But I guess we keep learning from the opposition when we do bowl second, and I guess that fuller length and that straighter line for me, attacking those stumps, it is pretty much part of my game-plan.

"I think as a bowling unit today, we were fantastic to keep such a good side to under 160. So it was a great performance by everyone."

The simplicity of Australia's methods with the ball make their earlier struggles to find serviceable back-ups to Starc and Pat Cummins something of a mystery. But with Jason Behrendorff adding another oppressive left-arm option to their ranks, and with Nathan Lyon's Test-honed killer instincts delivering another inch-perfect spell on a worn surface, there was never any real opportunity for New Zealand to free their arms and catch up with an escalating rate.

Starc, however, does not yet believe they have stumbled upon the magic formula for guaranteed success.

"I think the fantastic thing about our 15 guys is we've got guys that can open the bowling. We have got several guys that make up good combinations. We've had all 15 part take part so far in the tournament. Guys are ready to go if called upon. The guys that were picked today did another fantastic job, [but] I don't think we've quite played the perfect game, if you like.

WATCH on Hotstar (US only): Full highlights

"We're finding ways to scrap and to restrict teams, and we keep improving every game. But I think the turning point was probably that Indian game where we had a good chat as a bowling group and a batting group and we've just continued to improve as a whole group of players from that game, so it's been fantastic."

Until the start of the World Cup, Starc had been an onlooker as Australia set about their quiet resurgence of white-ball fortunes. He missed the 3-2 series win in India with a pectoral muscle strain, and was still on the road to recovery when they went on to beat Pakistan 5-0 in the UAE in March. But having returned to Australia's set-up he has recognised a side that had renewed belief.

WATCH on Hotstar (India only): New Zealand's innings

"From all reports, it's been a fantastic feel around the group in the UAE and India," he said, "and to play some fantastic cricket heading into that April break, was probably the momentum that the group was after heading into this tournament.

"So I think our chances are as good as any other team. We've always spoken about peaking towards the back end of the tournament, and we're still searching for that perfect performance. We're not quite there yet. We're showing glimpses of what we are capable of with the ball and with the bat and in the field, but we have still got room to improve, and that's exciting for this group.

"And if we can do that - well, we've got to play our best game in the semi now and hopefully better that in the final - and that's what tournament play is all about."

Andrew Miller is UK editor of ESPNcricinfo. He tweets at @miller_cricket