CNN  — 

There’s been no shortage of twists and turns in the buildup to the 2019 Rugby World Cup, which makes the task of predicting a tournament winner more difficult than ever before.

Japan and Russia kick off the tournament in Tokyo on Friday, six weeks – or 48 matches – before a champion is crowned at the International Stadium Yokohama on November 2.

New Zealand is going in search of an unprecedented third successive title, and until recently would have been most fans’ pick to do so.

The All Blacks are still the bookmakers’ choice, but losses to Australia, South Africa and Ireland mean that aura of invincibility has been tarnished.

All those teams, plus 2003 champion England and Wales – which enjoyed a record run of 14 games undefeated earlier this year – are the strongest contenders. That’s before you consider the likes of France – historically a strong performer at World Cups – and Argentina, always competitive with the world’s best sides.

The previous eight World Cups have produced just four different winners, but Ireland and Wales – both of whom have enjoyed recent stints at the top of the world rankings – are the most likely candidates to write their names onto the Webb Ellis trophy for the first time.

With plenty to dissect in advance, CNN Sport asked some of the World Cup’s familiar faces – from record try-scorers to past winners – to predict the 2019 tournament winner, which team might spring a surprise and potential stars of Japan 2019.

BRIGHTON, ENGLAND - SEPTEMBER 19: Japan players celebrate after the win over South Africa during the Rugby World Cup 2015 Pool B match between South Africa and Japan at Brighton Community Centre on September 19, 2015 in Brighton, England. (Photo by Steve Haag/Gallo Images/Getty Images)
Rugby players advised to cover tattoos in Japan
01:28 - Source: CNN

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Who is the favorite?

Former Wales captain Sam Warburton: It’s so difficult. I’m not really comfortable with saying any one team but if I had to I’d say South Africa. I don’t know why but they’ve had some really big performances in the last 12 months. They’ll get through the group stages and I think they’ve still got another six or seven weeks to build to a quarterfinal and they’re going to get better and better.

Former Ireland captain Brian O’Driscoll: If I had to pick a favorite I’d probably still go back to one of the previous winners. England are really showing well, they’re just peaking at the right time and have a nice blend of power and pace in forwards and backs. Good goal-kicker, good skill levels, and I just think if they can get lucky with injuries they’ll be right in the mix. The reemergence of South Africa is good for the game as well so maybe a final between those two.

2003 World Cup winner with England, Lawrence Dellaglio: Let’s make no bones about it, New Zealand are still the team to beat. Although they’re not the number one side in the world they have been the most consistent side. Their win ratio is over 90%, there’s not many sides that can say that. They’ve won the last two World Cups. They’ve got a coach who’s won the last two World Cups and their squad is packed with players who have won the World Cup already.

Former Wales wing Shane Williams: I think it’s exciting because we’re going into World Cup now as Welsh people, victorious in a string of games, Grand Slam champions, taking some big scalps along the way in a World Cup year, so that’s great for us. We’re very confident as a nation now, the players, having spoken to the likes of (captain) Alun Wyn (Jones) are looking forward to the World Cup to start. I’m going to back the boys.

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Which sides could cause an upset?

Past tournaments have been known to produce rather lopsided scorelines. Australia hammered Namibia 142-0 in 2003, and England put 111 past Uruguay in the same year. But that’s not to say upsets don’t occur.

Japan’s victory over South Africa in 2015 is widely thought to be the greatest upset the sport has ever seen, and the match, which took place on England’s south coast, has been retold in a recently-released film, “The Miracle of Brighton.”

So which team could write its own movie script this year?

Former South Africa wing Bryan Habana: I think Fiji are going into this World Cup as a team that could really upset the apple cart. They’ve got some players that are plying their trade in the northern hemisphere, the Top 14, the Celtic league and in the Premiership. The quality of those players is incredibly special. They’ve done some incredible things in a very short period of time now and if one looks back to 2007, bar a tackle from JP Pietersen in that right-hand corner (South Africa) were probably about five to 10 minutes from losing that game. So I think that Fijian flare could be a very difficult banana not to slip on.

Fiji's Josua Tuisova scores in a victory over France last year.

Sam Warburton: Unfortunately for me as a fan, they’re both in Wales’ group. You’ve got Georgia and Fiji. Georgia have been an emerging country for quite some time now and they’re making some noise in the last few years. This is going to be an amazing shop window for them and they’ve got other agendas – like trying to get into the Six Nations – that they desperately want. This is going to be a platform for them to demonstrate how good they are. And Fiji, if they can get everything coordinated together from their fitness regime, their training plan, their team structure, genetically they’ve got the best athletes on the planet. People are expecting Wales to win by maybe 20 or 30 points but one of those is going to be a one-score game, it’s going to be a tight game. They’ll be two tough teams I think who will excite people.

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2003 World Cup winner with England, Will Greenwood: I think Japan will beat either Ireland or Scotland (in the group stages). I think Japan could win one of their two big games. Fiji could scare the living daylights out of Wales and Australia if you go in with a backline that’s got (Levani) Botia and (Semi) Radradra in the middle and you’ve got (Vereniki) Goneva and (Josua) Tuisova at 11 and 14, and (Semi) Kunitani the Olympic Sevens legend at seven, they could do anything there.

Italy flanker Sebastian Negri: I’d be lying if I said we (Italy) didn’t want to get out of our pool (over New Zealand or South Africa). That’s a realistic and an ambitious goal. We have to take one game at a time but we want to make history and do everything that we can to get out the pool. It’s not easy, it’s a massive challenge but we’re going to do everything we can and really work hard together to try and create history for Italy, I think that will be something very special.

Who are the players to watch?

There have been some stunning individual performances in the Rugby World Cup’s 32-year history.

Jonah Lomu steamrollering England’s defense to score four tries in the 1995 semifinal, Jonny Wilkinson’s winning drop goal in 2003 and Thierry Dusautoir’s record 38 tackles against New Zealand in 2007 all stand out, and the stage is now set for new players to set the rugby world alight.

Sam Warburton: One player I’ve mentioned a few times is Joe Cokanasiga for England. I saw him play against the Barbarians a few months ago and he’s just got that X-factor, that stardust that you need in the backline where he can create something from nothing. I’m looking forward to seeing him on the world stage. I can imagine him just excelling on that world stage and really announcing himself as a world class winger. I’d love to see it from a spectacle point of view. We need people like that in the game, big, exciting, skillful wingers.

Lawrence Dellaglio: I really want to see Billy Vunipola on the big stage. He’s played a lot for England but he’s had a few troubles with his arm and everything and as a number eight I think his time has come. I’d really like to see him have a dominant tournament and be at the forefront of England winning that. That for me would be a success. Damien Penaud in the French team is a serious player. I’m old enough to have played against his Dad, actually. The French backline looks pretty good – but hopefully not against England.

Damian Penaud celebrates scoring against Scotland earlier this year.

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Bryan Habana: Being a winger and looking at the guys, Cheslin Kolbe has been absolutely phenomenal since getting his first taste of international rugby in New Zealand last year in that very famous victory down in Wellington. He’s been lighting up fields in the northern hemisphere in the Top 14 and the Heineken Cup and he’s been doing the same for the Springboks. If ever anybody embodied dynamite in small packages it’s him. I’m looking forward to him hopefully setting this World Cup alight.

Brian O’Driscoll: I’m looking forward to seeing Damien Penaud who’s lighting it up with France at the moment. He’s looking like a bit of a try machine. He was very good at the Six Nations. He looks like a French player of old, something we might have seen back in the 80s in his father’s heyday. He looks as though he’s got electricity in his legs. Something’s going to happen when he gets the ball, he’s got that excitement about him. Those are the sorts of players you want on the big stage and to propel themselves in front of the world and to show their talents off. I hope from his perspective and from France’s perspective they’re going to get into the knockout stages at least.