The clock at the National Stadium showed 00:00. Australia held the slimmest of leads at 22-21.

All Fiji had was a scrum, 90 metres and seven Aussies between them and a very unlikely triumph at the HSBC Singapore Rugby Sevens yesterday.

It was a mountain to climb - even for the free-spirited, free-flowing Fijians - but they believed. And they pulled it off.

"I was running from the back and cheering. Alasio Sovita Naduva and I are from the same island in Fiji, and I was thinking, 'Go, go, run, run'," said Fiji skipper Jerry Tuwai.

"Back home, we have this belief that nothing ends before the final whistle. There's always still time, we still have a chance - and today, it did go our way."

Naduva evaded tackles, turned on the after-burners and flew through the air to score the final try that would break Australian hearts, as Fiji ran out 28-22 winners.

"It was not even the last minute, it was zero on the clock, and he dived right between the posts. That has to be my happiest moment in Singapore," said Fiji's World Series debutant Keponi Paul.

But the outcome could have been very different. Right before referee James Doleman brought the play back for a scrum - awarded to Fiji for an Aussie knock-on - Australia thought they had scored a try that would take the game beyond Fiji. The celebrations even started on the bench.

"It hurt, especially after we thought we had won it. We were celebrating and then we realised that it was a scrum - it was obviously disappointing," said Aussie coach Tim Walsh, who helmed the men's team for the first time in Singapore.

"What we needed to do in those last 30 seconds after that scrum was to make our tackles, and we didn't. (To finish second in my first outing is) not too shabby. It's good, but not great."

Fiji are the third different winners of the Singapore Sevens since the World Rugby Sevens series returned to the Republic in 2016. Kenya won that year, with Canada triumphing last year - both were first-time winners of a series leg.

The sensational win sees Fiji overtaking South Africa at the top of the World Series standings. They now have 145 points, four ahead of the Blitzboks, who finished fourth in Singapore after losing 24-26 to England in the bronze-medal match.

New Zealand are third on 120 points, with Australia on 108 points in fourth spot.

Fiji are in the driver's seat with two legs remaining - London and Paris - but they are not taking anything for granted.

"We came here aiming to win in Singapore because of the World Series standings, and I think we achieved our goal as a team, but it's not done yet," said Tuwai.

"Right now we are happy that we are on top, but there's still a lot of work to be done in London and Paris."

Fiji were not the only winners, with Singapore receiving several plaudits as well. The two-day event attracted over 55,000 fans, according to the organisers.

"This is different to the Dubai and Hong Kong Sevens, and I dare say the best of all of them. It's a great family event, and I enjoyed the atmosphere, the activities for children and the food and drinks," said Englishman James Atwell, who came with his wife and two children aged nine and 11.

"Access to the players was really important for them, and they got it. We all had a great time here."

For Aussie coach Walsh, Singapore will surely be synonymous with their gut-wrenching defeat, but he had nothing but praise for the host city that is bidding to retain the World Series beyond 2019.

"Coming from the women's circuit, it's a beautiful stadium, and the surface is great. The flow from the changing rooms to the warm-ups to here on the pitch, is effective," said Walsh, who previously coached Australia's women's sevens side.

"No complaints from the players and the staff, we've been on the circuit for years, and we think it's up there with one of the best on the series. Great stuff, thank you Singapore."