The sixth Rugby World Cup gets under way at 2000 BST on Friday when hosts France take on dark horses Argentina in front of an 80,000 crowd in Paris.
France are aiming to win the World Cup for the first time
It is the first of 48 matches spread over 44 days with 20 teams playing in 12 different stadia.
New Zealand are strong favourites while champions England, who start against the USA on Saturday, try to become the first team to defend the title.
Wales, Scotland and Ireland begin their campaigns on Sunday.
Four years ago in Australia, Jonny Wilkinson's famous last-gasp drop-goal gave England a gripping 20-17 win over the hosts and made them the first northern hemisphere side to win the trophy.
But the champions, who are in the same group as many pundits' second favourites South Africa, have slipped to seventh in the world rankings since 2003, and are without the injured Wilkinson for at least their opening game.
Despite a record of five defeats in their last six Tests and a dismal away record in recent times, coach Brian Ashton insists talk of reaching the semi-finals being a successful outcome is misplaced.
"There is no minimum ambition for a World Cup, you have just got to go and win it," he said. "The pressure side of it has disappeared. I hope the players are relishing the challenge of doing something that has never been achieved before."
The pressure of starting favourites is firmly on New Zealand, who have dominated world rugby since the last tournament, winning 38 of their 43 Test matches and only losing one game a year in the last three years.
However, the All Blacks have lost in three semi-finals (1991, 1999 and 2003) and one final (1995) since winning the inaugural World Cup 20 years ago.
Current captain Richie McCaw, one of the finest players of his generation, acknowledges his career will be incomplete without a World Cup winners' medal.
"It's definitely going to define me, and it's going to define this team," he said of the forthcoming tournament.
The Eiffel Tower was lit up to celebrate the start of the Cup
"We've been pretty successful over the last four years, but what happens in the next six weeks will be how you remember what this team is about."
France, who have never won the Webb Ellis trophy, hope the tournament will feature a similar conclusion to the 1998 football World Cup, when the Champs-Elysees in Paris was lined with millions of people after the hosts' shock victory over Brazil in the final.
"It was a huge event," recalled Sebastien Chabal, the bearded France forward who is a cult figure at English club Sale.
"There were 10 million people in Paris and it was unbelievable.
"If we can do the same as the football team, then I think we will have the same support behind us. We think a lot about winning the World Cup and I think we are in the right position to start the tournament."
France are in the "group of death" with Ireland and Argentina - all three teams are in the top six in the world rankings.
Ireland know that finishing second in the group will probably bring a quarter-final clash with the All Blacks in Cardiff.
New Zealand are expected to comfortably top a group that also features Scotland and Italy, who meet in a decisive pool game on 29 September.
Wales have Australia, the only country to have won the tournament twice, in their pool, but play the Wallabies in their Millennium Stadium home a week on Saturday, 15 September, with Canada, Fiji and Japan making up the group.
We are ready and we will show a good face to the world
French rugby chief Bernard Lapasset
Cardiff is one of two venues outside France to stage matches, the other being Edinburgh's Murrayfield, which will host Scotland against New Zealand and Scotland against Romania in the pool stages.
The semi-finals and final will be at the Stade de France in Paris, with Bernard Lapasset, the president of the French Rugby Federation, convinced the hosts will put on a memorable World Cup.
"I feel sure it will be a big success," he said. "There has to be a good spirit in the stadiums, a sense of empathy between player and public.
"But there has to be more than that. We in France have to demonstrate we can organise a big event. But we are ready and we will show a good face to the world."
Lapasset, Bertrand Delanoe, the mayor of Paris, and International Rugby Board chairman Dr Syd Millar kicked off the festivities on Thursday night by lighting up a giant rugby ball suspended between the lower pylons of the Eiffel Tower.
The official opening ceremony will take place at 2020 (1920 BST) on Friday at the Stade de France before the hosts and Argentina kick off the action.
The build-up to the event has been marred by an on-going row between a number of media groups and the tournament organisers.
The media groups are boycotting official events in protest at restrictions over what coverage they are allowed to provide.
As a result most British newspapers did not carry tournament-related pictures in their Friday editions.