When the team sheets come out for the Cricket World Cup final, New Zealand's will be topped, as always, by Martin Guptill.

Maybe only his teammates will expect much from him on Sunday at Lord's. Most will wonder how soon England gets him out.

It's been that bad for Guptill. The top gun of the 2015 World Cup has been a mere pop gun four years later. From top run-scorer in 2015 to just fifth best on his team, he's enduring a horror run.

And yet, when he's not batting he's turned out to be one of the stars of the World Cup, as a fielder. Guptill could own the best catch of this tournament, and the best run out.

The change in starring roles surprises. Guptill came to the World Cup fresh off consecutive centuries. He'd averaged 50.01 since the last World Cup. He was the explosive opener who softens up the ball and the opposition attack for Kane Williamson and Ross Taylor to pile on the misery in the middle overs.

Only, Guptill's string of batting failures has burdened Williamson, who has risen to the occasion, and Taylor, who has been hit and miss.

“Even in the nets I've found I've been wanting a bit, late on the ball,” Guptill told New Zealand's 1 News.

“I've put a lot of time in and for it not to be working out in the middle it's frustrating. People can say they're frustrated with me but no one is more frustrated than what I am.

“I'm just trying to carry on with what I've been doing, work hard in the nets, and hopefully in the next game it all comes together.”

The World Cup started great for Guptill, an unbeaten 73 in a winning chase of 137 against Sri Lanka. However, he was fortunate that before he scored, the second ball he saw and edged off Lasith Malinga fell in front of second slip. From that 73, he's gone downhill, fast.

His next best score was 35, three games later against South Africa. He was cruising, hitting three boundaries in four balls against Lungi Ngidi. But after hooking Andile Phehlukwayo, Guptill planted his foot to run only to slip, and slide his foot into the stumps. He became the 10th batsman in World Cup history to be out hit wicket.

When he was surprised by an in-swinger from Afghanistan's Aftab Alam, Guptill became only the second New Zealand opener to be out first ball in a World Cup match, after John Wright. Incredibly, Guptill repeated the golden duck two games later against the West Indies, which was only too glad to see the back of him. Guptill humiliated the Windies in the 2015 quarterfinals with 237 not out, the highest score in World Cup history.

He averaged 68 in 2015, luxuriating in home conditions to lead New Zealand to its first World Cup final. This time, on soft, tacky English pitches in which it has been hard to hit away, he's averaging 20.87. He's in his worst scoring rut in ODIs in nine years.

His failure to launch seems to have infected fellow opening batsmen Colin Munro and Henry Nicholls. Munro played the first six games. He's averaging 25. Nicholls, a middle-order batsman converted to try and replace Munro, is averaging 12. After that unbeaten 137-run stand against Sri Lanka in the first match, New Zealand's opening partnerships have combined for only 84 runs in eight innings. The confidence at the crease of all three openers is low.

And yet, New Zealand has still made a second straight final. A bonus. And Guptill will be there. Double bonus. Because he's been the standout example of New Zealand's mantra of adaptability, by setting aside his batting woes and being a star in the field.

He has eight catches, double from 2015. The only non-wicketkeepers with more catches are other close-in fielders Joe Root, with 12, and Faf du Plessis, 10.

And some of Guptill's feats have been spectacular.

At second slip against Sri Lanka, he took a good low catch to his left to see off Kusal Mendis for a duck, and give man-of-the-match Matt Henry a third wicket inside nine overs.

Guptill came from point to dive full stretch and catch out at grass height his second Pakistan opener Imam-ul-Haq.

Against Australia, Guptill spilled hard chances against Aaron Finch and Usman Khawaja before they scored, then showed amazing instinct to get his over-balanced left mitt high to pouch a full-blooded pull by Steve Smith. TV analysis showed Guptill was standing 17 metres away, and had 0.6 seconds to react.

Guptill also ran out Haris Sohail with a full-stretch dive to the bottom of the wickets, and clinched New Zealand's semifinal upset of India when his direct throw on the run from almost side on to the stumps hit them directly, stranding MS Dhoni by two inches in the 49th over.

“He's probably the only man on the pitch that could create that run out,” Williamson said. “Contributions can come in so many different ways and we've seen on the fielding charts he's been right up there. For him to do that and pull off what was a significant turning point in the match was special.”

The ability to thrill, Guptill hasn't lost.