SOUTH AFRICA
Previous World Cup best: Winners (1995, 2007)
Head coach - Heyneke Meyer: All coaches of the established nations at the World Cup are under pressure, but there is probably more on Meyer than most. Being the head coach of South Africa is undoubtedly one of the toughest jobs in rugby, such is the demand for success. That is something that Meyer has struggled to provide since his appointment in 2012, culminating in a first ever defeat to Argentina earlier this year. Failure to impress over the next few weeks may cost the 47-year-old his job.
Key player - Duane Vermeulen
The number eight has recently been recovering from neck surgery, but he has been deemed fit enough to be included in the Springbok squad. Vermeulen, who is nicknamed Thor, is known for his explosive qualities and hitting hard in the tackle. The 28-year-old has agreed to join Toulon after the tournament, so there will be no doubt that he will be looking to show his new employers what they have got on rugby's biggest stage.
Sports Mole says: South Africa have lost four on the trot in 2015, including that humiliation at the hands of the Argentines which saw Meyer's men finish bottom of the Rugby Championship for the first time. As a result, they dropped down to fifth in the world rankings and although they have since risen to third, that is only owing to recent defeats suffered by England and Ireland. On paper at least the pool is a favourable one, which should help to build confidence. Yet, winning the tournament for a third time may very well be beyond them.
SAMOA
Previous World Cup best: Quarter-finals (1991, 1995)
Head coach - Stephen Betham: It's well known that Betham was not Samoa's first choice when the job became available in 2012. Australian Adrian Thompson was the preferred option, but when he refused to live in Samoa, the role went to Betham, who had been in charge of the country's sevens team. The former Samoa Under-20 international had success at sevens level and will now be hoping that he can take that into the XV format of the game.
Key player - Kahn Fotuali'i
Physical and nimble in equal measure, there is going to be a big onus on the scrum-half over the next few weeks. Samoa's trademark is to battle in the set pieces and all eyes will be on Fotuali'i to ensure that they make the most of it. It's also vitally important that the Northampton Saints player stays clear of injury when you consider that the only replacement in the squad is Vavao Afemai, who is a Samoa-based amateur.
Sports Mole says: Results may have been more down than up over recent months, yet there is still reason for optimism for supporters of the Samoan team. Twelve of the squad are based in Britain, three of whom (Fotuali'i, George and Ken Pisi) were part of the Northampton side that made it to the semi-finals of the Aviva Premiership and the quarter-finals of the European Rugby Champions Cup. They have also beaten the Scots in recent years, so will fancy their chances of progressing to the quarter-finals as runners-up to South Africa.
SCOTLAND
Previous World Cup best: Semi-final (1991)
Head coach - Vern Cotter: Following an impressive eight-year stint in charge of Clermont Auvergne, Cotter's arrival as the Scotland boss was met with much positivity. The New Zealander had a good opening autumn in charge, but a winless 2015 Six Nations campaign has sucked out the majority of that good feeling. Having made some controversial squad selections, the pressure is now on the 53-year-old to deliver tactically.
Key player - Finn Russell
There has been plenty of interest from Aviva Premiership clubs in Russell's services over recent months, but he put an end to speculation regarding his future earlier this week when he signed a new contract with the Glasgow Warriors. Now, with that settled, the 22-year-old can put his entire focus into the World Cup. With Scotland expected to play direct, the No.10's execution is going to be vital to their chances. Although his international career may be in its infancy, Russell has already shown himself to be a good replacement for Gregor Townsend.
Sports Mole says: As far as getting out of the pool is concerned, it's likely to come down to one match for Scotland. Wins should be achieved against Japan and the USA, with a defeat against South Africa to follow. That will leave the clash against Samoa in Newcastle on October 10 as a straight knockout. Failure to get out of the pool four years ago, as well as the disastrous Six Nations campaign earlier this year, means that expectations are relatively low. However, a recent comprehensive warm-up win over Italy has lifted spirits a notch or two.
JAPAN
Previous World Cup best: Pool stage (1987, 1991, 1995, 1999, 2003, 2007, 2011)
Head coach - Eddie Jones: The 55-year-old is best known for his stint in charge of Australia, which included being at the side's helm when they lost the 2003 World Cup final on home soil. The team's form after that defeat to England was poor, which ultimately cost Jones his job. Since then he has had a spell in charge of Saracens, before being appointed as Japan head coach in 2012. On a personal level it's not been all plain sailing for Jones, who suffered a stroke in 2013. He will step down after the tournament.
Key player - Ayumu Goromaru:
Japan often enjoy walkovers against their fellow Asian nations, but the fact that Goromaru was the most prolific points scorer in international rugby last year should still be respected. The 29-year-old full-back is Japan's designated kicker - a role that he flourished in during the recent 20-6 victory over Canada at the Pacific Nations Cup when he scored five penalties from six.
Sports Mole says: Jones has insisted that his side have travelled to England determined to reach the quarter-finals for the first time in the competition's history. While there is nothing wrong with ambition, the fact that Japan have won just one World Cup game - 24 years ago - would suggest that progression is highly unlikely. On the flip side, they have picked up recent victories over Samoa and the Americans, but when it really matters, they are likely to come up short.
UNITED STATES
Previous World Cup best: Pool stage (1987, 1991, 1999, 2003, 2007, 2011)
Head coach - Mike Tolkin: The English teacher took over as head coach of the USA in February 2012 from Irishman Eddie O'Sullivan. His experience of coaching at senior level is limited, but he was the defence coach of the Eagles squad at the 2011 World Cup. Tolkin made himself a popular figure in 2014 when he guided the Americans to their first victory over Canada in five years.
Key player - Chris Wyles
After spending a number of years playing in England with Saracens, Wyles has developed into an impressive player that is capable of playing across the backline. The 32-year-old is a prolific scorer of tries, highlighted by the 13 that he ran in during the 2014-15 campaign - only Thomas Waldrom of the Exeter Chiefs scored more. He also has a vast experience at international level from his outings at the World Cups in 2007 and 2011.
Sports Mole says: The coach and playing squad are saying all the right things and come across as a positive bunch, but it would be a big surprise were the USA not to finish bottom of the pool. Of the 31 players in the squad, just 11 have been in the World Cup environment before. The defence in particular is naive, which could see Tolkin's men ship plenty of points.
Pool B fixtures
Saturday, September 19
South Africa vs. Japan
Sunday, September 20
Samoa vs. USA
Wednesday, September 23
Scotland vs. Japan
Saturday, September 26
South Africa vs. Samoa
Sunday, September 27
Scotland vs. USA
Saturday, October 3
Samoa vs. Japan
South Africa vs. Scotland
Wednesday, October 7
South Africa vs. USA
Saturday, October 10
Samoa vs. Scotland
Sunday, October 11
USA vs. Japan
Prediction: 1. South Africa 2. Samoa 3. Scotland 4. Japan 5 USA
