Rugby was played to a predictable rhythm in the Five Nations back then; it bumbled along between set pieces and high kicks and there was a sort of gentleman's agreement that tackling would be from the hips down.
Samoa brought a new dimension - they were explosive and creative; hit men in the chest and played as if they were never going to be held prisoner by a predetermined game plan.
It was a captivating and exhilarating campaign that changed rugby's landscape forever.
Peter Fatialofa, captain of the 1991 side, can remember returning home after Samoa's quarter-final defeat to Scotland and realising things were going to change quickly.
When he first began playing in Auckland in the early 1980s, rugby was a game for Europeans. The Pacific Islanders he knew either didn't bother or would play in their own teams, usually affiliated to their church.
His call-up to the Auckland team in 1985 was a major surprise - he had never seen himself as a provincial prospect, partly because he didn't feel he had the goods and partly because Polynesian players featuring at that level was rare.
"I came into rugby late and when I came into the Auckland team and saw players like Andy Haden, I couldn't help but wonder what I was doing there. I was a bit rough around the edges and all of a sudden, I had to pull my head in. Fitzy [Sean Fitzpatrick] demanded excellence and I quickly realised I was going to have to change if I was to stay in the team."
Fatialofa, universally known as Fats, imposed some of those same demands on his 1991 Samoan team which was partly why they were so successful.
With former All Black Bryan Williams as coach and players such as Pat Lam and Frank Bunce who had been around the New Zealand provincial scene, Samoa were able to meld together a hypnotic concoction of raw power, natural talent and just enough discipline to beat Wales, then push Australia to their limits in Pontypool and finish the pool with a spectacular win against Argentina. By the time the Samoans headed to Edinburgh for the quarter-finals, they were a serious threat.
"I knew we were going to be opening some doors with the way we were playing at the World Cup," says Fatialofa.
Those doors opened. If there had been a reluctance to pick Polynesian players before 1991, there was no evidence of it afterwards. Lam, Bunce and Stephen Bachop all become All Blacks after that campaign. Others such as Perelini ended up in Europe, where he played league.
Once the game went professional in 1996, the appetite for Pacific Island players became voracious. They were comparatively cheap and brought a uniquely explosive package.
In New Zealand, the Pacific Island influence became enormous almost overnight. The big stars were all Polynesian - Jonah Lomu, Inga Tuigamala and Tana Umaga. The numbers of Pacific Islanders in representative teams exploded, as coaches looked for ball carriers and big tacklers. The influence of Pacific Island athletes could be seen in the changing ethnic make-up of the All Blacks. In 1999, there were six players in the All Black squad with Pacific Islands heritage; in 2003, it was nine, and in 2007, it was 11. This year, there are eight, but the Pacific influence is now enormous across the entire World Cup.
There are seven players of Polynesian heritage in the Australian team; seven in the US team; three in the Japanese team and there is the Samoan Manu Tuilagi playing for England and the Tongan-born Toby Faletau playing for Wales.
There are 120 players at this World Cup who were either born in the Islands or consider themselves Pacific Islanders: that's 20 per cent of all the players drawn from three tiny island nations whose combined population is barely a million.
Fatialofa says they had some sense of the impact they were having back in 1991. But he didn't really. No one thought Samoans and Tongans would stand at Twickenham wearing England jerseys while booming out God Save the Queen, as both Tuilagi and Lesley Vainikolo have done.
No one thought there would be times when the Blues would field 15 Pacific Islanders or that the biggest clubs in Europe would all insist on having at least one Polynesian wing.
Least of all did anyone think that a game between Fiji and Samoa would sell out Eden Park and turn swathes of Auckland into Suva and Apia.
"I think what we have now," says Fatialofa, "is a situation a bit like in the USA, where rugby is it like basketball for kids in the ghetto. It is a legitimate career for the Pacific Island boys and more and more are becoming professional players."
Today's game remains a must win for both teams. Both have an outside chance of making the playoffs. Samoa remain confident they can topple South Africa next week and make it; Fiji beat Wales in their last pool game of 2007 to push into the last eight and will fancy they can do the same again.
But to an extent, it won't really matter who wins today. Auckland is going to have a giant party whatever happens. Samoa did more than put themselves on the world map 20 years ago - they put all of the Pacific Islands on it and today is about acknowledging the massive contribution these tiny islands have made to world rugby.
