Debutant Jack Bostock almost single-handedly stole the Rugby League World Cup opener, with three tries and one crucial try assist in a 24-22 victory over New Zealand that might generously be described as undeserved.

The Dolphins player wrestled a Cameron Munster kick away from Jamayne Isaako in the air with five minutes to go to complete his treble, putting his side in the match-winning lead. It was a carbon copy of his second try, as he proved damaging under the high ball. But it was his first four-pointer – a length of the field intercept midway through the opening half – that told the story of this extraordinary match.

This should have been a Kiwi victory. Their pack dominated the Kangaroos, and the star of the show was Kiwi fullback Kalyn Ponga. He overcame a painful arm injury to score two tries, and the second was a declaration of his arrival as – with Nathan Cleary injured – the best player in rugby league.

With 20 minutes to go, the Knights' champion brushed off Cameron Munster and stepped around Reece Walsh with his shorts halfway down his thighs. The player known for the fluorescent red headgear at Newcastle wore black on his melon tonight. But his underwear shone pink, as his hips swung in and away past the Kangaroos' No 1.

Briefly it looked like Walsh had levelled the scores again moments later, but a desperate tackle from Jahrome Hughes and Dane Gagai brought him down within centimetres of the line. His awkward attempt at the put down was fairly ruled a double movement.

Walsh would not be denied his time in the spotlight, however. In the 68th minute, he ran on to an offload from Bostock coming out of his own end. The young winger carved out a half break, but handed it to Walsh whose sweeping run forced Hughes and Ponga into a collision before the No 1 crossed in the corner. The try brought the margin back to two, paving the way for Bostock to secure the remarkable result in the dying stages.

The weather had not delivered on this first night of the tournament in a chilly, wet evening in Sydney, but something else soon rained down from the heavens. It was Kiwis' centre Casey McLean leaping around the sideline, through the tackle of Mitchell Moses and inside the corner flag to plant the ball for a gem of an opening four-pointer.

The try followed a Hughes bomb targeting Tom Trbojevic. Ronaldo Mulitalo intercepted the falling ball, and his bat back found Isaiah Papali'i who sent it wide to McLean. The highlight was a vindication for this year's State of Origin eligibility laws, which has allowed players like the boom NSW Blues centre to play for someone else other than Australia.

The Kangaroos enjoyed little attacking field position until almost 15 minutes in, but a knock-on from Harry Grant – called by the video referee – ruined what would have been a repeat set. The Melbourne hooker is considering testing the market next month, but his early display will have given his agent food for thought.

The Kiwis, by comparison, looked money. They should have scored again 20 minutes in when Ponga helped create an overlap. Hughes' lofted cut-out was read well, however, by Bostock. The winger caught it and covered the length of the field for an undeserved jackpot, making it one try apiece.

The going was all New Zealand, but then the unthinkable happened again. This time Trbojevic snaffled a pass from McLean that would have put Mulitalo over. He shook off Kodi Nikorima on the chase to level the scores, before Walsh added the two to secure the lead.

Suddenly Ponga was through the line and certain to score, but Walsh forced him over the line in a sensational stare-down between the game's two most electric No 1s. But Walsh ruined his good work with a handling error seconds later. From the next set, another Hughes kick forced Staggs into grabbing Nikorima on the chase. It was not quite a penalty try, but a sin bin and two points to level the scores at half-time.

The Kiwis had dominated the first half, running for more than 1,000 metres. It was roughly 300 more than Australia, but take out those two intercept tries and a fairer picture emerges. The Kangaroos were brutalised, and their average set distance was just 37 metres compared to the Kiwis' 49 metres. Tackles were 195 by Australia, 129 by New Zealand.

The second half was more even, but New Zealand were left to rue their missed opportunities. The exit of Ponga with his arm injury late in the match will also be a concern given the final – and a likely rematch against the Kangaroos – is less than a month away.