Some of the most memorable moments in Rugby World Cup history have come from unlikely sources.
In 1991, Samoa started the tradition by upsetting Wales 16-13 at Cardiff Arms Park. Then they handed the Welsh their first-ever defeat at Millennium Stadium in 1999.
In 2015, Japan beat South Africa to pull off one of the greatest rugby - if not sporting - upsets of all time.
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And most All Blacks fans have probably tried to block the memory of how France sent New Zealand packing from the tournament in the 2007 quarter-finals.
This year’s tournament presents more opportunities for underdogs to shine and we highlight the most likely suspects.
Japan will have everything to play for when they host their first ever Rugby World Cup.
The side will hope to build on a 2015 tournament that saw them pull off one of the greatest upsets in sport by defeating South Africa.
Four years on, Japan have a similar pool to contend with, but this time, they have the power of home fans in home stadiums and a far friendlier schedule.
With victory over Russia a certainty and a win likely against Samoa, the side's last match in Pool A is against Scotland - a side with a poor away record - and they'll have eight days of rest, before taking them on.
Look out for fireworks come October 13.
Players to watch: Michael Leitch, Ataata Moeakiola
Let's face it, Argentina's recent form has been questionable.
An away win over Australia in the 2018 Rugby Championship, and close losses to New Zealand and South Africa were impressive, but those results were bookended by losses to Welsh and Scottish 'B' teams, along with away defeats to Ireland, France and Scotland.
But they tend to rise at Rugby World Cups.
They finished third at the 2007 tournament, after defeating hosts France in pool play. They also progressed past pool play in 1999, 2011 and 2015, making the semi-finals in the latter.
Their pool sees them needing to beat USA, Tonga, and likely one of France or England to progress.
Players to watch: Agustin Creevy, Bautista Delguy
As two-time quarter-finalists, Fiji have an impressive World Cup resumé.
Of their campaigns, the most memorable was arguably that of 2007, in which they eliminated Wales, before giving South Africa a genuine fright in the final eight.
Since 2014, the side have recorded notable wins over France, Italy, Japan, Samoa and Scotland, and are now ranked ninth in the world.
Fiji's biggest chance at an upset looks like their opening fixture against Australia on September 21.
Players to watch: Leone Nakarawa, Semi Radradra
Samoa are currently ranked the lowest of all the major Pacific Island rugby nations, yet their history and pedigree suggest they could still cause an upset at the tournament.
Samoan sides have made it through to the quarter-finals three times - in 1991, 1995 and 1999. Since then, their World Cup form has been shaky.
But with a roster that includes the likes of Tim Nanai-Williams, Alapati Leiua, Tusi Pisi, TJ Ioane, Jack Lam and Moto Matu'u, their potential is real.
The last time Samoa played Scotland, they lost by just six points at Murrayfield, and a result over Japan is not out of the question. Watch out, Pool A.
Players to watch: Tim Nanai-Williams, TJ Ioane
Georgia's ranking has steadily risen over the past decade and now they now sit 12th in the world, having languished around 20 for much of the early 2000s.
That ranking puts them ahead of the likes of Tonga, Italy and Samoa, and while they’ve never beaten a tier-one side, the potential is there for an upset.
Georgia defeated fellow Pool D side Fiji in 2016, so they’ll just need to repeat that feat, see off Uruguay, and upset Australia or Wales.
Given the size of their forward pack and typical tactics, Georgians should probably start the rain dances in Japan nice and early.
Players to watch: Beka Gorgadze, Zurab Zhvania.
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