Star player: Periscope. The Wallabies have been live streaming a number of events including team announcements and training sessions via the fast-growing platform.
Sin bin: @QuadeCooper - a key player in the team, earlier this year Cooper fell into that very modern of traps for high-profile athletes when an angry tweet got him in hot water. It was the second time he had been in trouble for social media indiscretions, having previously been hit with an AUS$60,000 (£27,600) fine by the Australian Rugby Union.
Fair play: A BuzzFeed article earlier this year picked out flanker David Pocock as one of Australia's most wholesome athletes on social media. "Team training shots, some great Australian bush shots and, of course, posts like this super-cute photo with his Gran are guaranteed to get you hooked on David," wrote Gyan Yankovich of Pocock's Instagram account.
In the posh seats: Officially known as the Qantas Wallabies thanks to their tie-up with the airline. The team is kitted out by sports apparel firm Asics, and other sponsors include HSBC, watchmaker Seiko, Bond University in Queensland and multiple tourism boards in Australia.
Star player: @jameshaskell is more followed than his captain, Chris Robshaw, on Twitter. Haskell uses his tweets to promote his own health and fitness business, banter with his team mates and, of course, England Rugby's sponsors.
Sin bin: England's poor performances and subsequent exit from the 2011 tournament were compounded by poor behaviour off the pitch - including the notorious 'dwarf-throwing' incident on a night out – and one of its players being fined for jumping off a ferry. The host nation will need to be on its best behaviour to avoid its brand going sour.
Fair play: The team’s Instagram account has been promoting the message ‘Rugby is good for you’, talking about the key values of the sport and the importance of player welfare, and encouraging participation by linking to the ‘Find a Club’ facility on the Rugby Football Union website.
In the posh seats: England have teamed up with the other home nations for a campaign for Lucozade, and another for Dove also involving their British Isles rivals. While shirt sponsor O2 has also run a major campaign including store rebranding, it might end up being trumped by this comic offering from Samsung Electronics UK, an official partner of England Rugby.
Star player: With star player Leigh Halfpenny now sidelined through injury, the most compelling individual story in Welsh rugby is a man who is not even playing anymore. Former captain Gareth Thomas’ struggle to come to terms with his homosexuality and the reaction of teammates after he came out is captured in this film for Guinness Europe.
Sin bin: In the Six Nations championship at the start of this year, concussion and head injuries came under the spotlight as key winger George North was sidelined. Part and parcel of the game though such injuries are, the rugby world would not relish this relatively underdeveloped area of science becoming a major talking point again during the tournament.
Fair play: The aforementioned Halfpenny has been a class act and a valuable asset to the Wales Rugby's brand off the pitch - posting a gracious and mature statement on Twitter after his injury heartbreak. He also gave some junior rugby players the surprise of their life in a video produced in alongside sponsor Land Rover.
In the posh seats: Booze is on the sponsorship menu for Wales - three of the Wales Rugby Union's principal partners are beer brands (Heineken, Guinness and Brains, for the record), while the team has also been working alongside England and the other home nations to promote both Lucozade and Dove Men+Care.
Star player: Forget all this business about brand values - the person in charge of Fiji's Facebook page is more interested in the score after 80 minutes, bullishly posting this English newspaper article suggesting the team posed a threat to England in the tournament's opening match. Confident stuff given that the island nation is a 12/1 outside bet to beat the hosts.
Sin bin: We know it can get exciting, but was it really necessary to live tweet your latest warm-up game ALL IN CAPITAL LETTERS???
FULL TIME AND FINAL SCORE FIJI 47 CANADA 18.— Fiji Rugby (@fijirugby) September 6, 2015
CANADA TRIED TO PUT THE BALL WIDE BUT WAS INTERCEPTED BY METUISELA TALEBULA AND HE SCORES FOR FIJI FIJI 47 CANADA 18— Fiji Rugby (@fijirugby) September 6, 2015
Fair play: It may surprise fans to find that Fiji's squad includes the son of a Cornish tin miner. Joel Matavesi was born to an English mother and Fijian player Sireli Matavesi, who came to England to play rugby and ended up staying and working down the minest in the 1980s. After Sireli was paralysed following an operation last year, the Cornish and Fijian rugby worlds came together in June for a fundraiser for the hospital where he now lives.
In the posh seats: Fiji's main sponsor is Vodafone, which recently committed an extra FJD$100,000 (£30,000) incentive payment to the team. Other sponsors include Fiji Airways, Coca-Cola and Carpenters Motors, a used vehicle trader based in Suva, the country's capital.
Star player: Put the term 'Uruguay rugby team' into a search engine of your choice is more likely to produce results about an ill-fated Old Christians Club team of 1970s than its present incarnation. In 1972, the team was in a plane crash high in the Andes that saw several die and survivors turn to cannibalism.
Sin bin: The Uruguayans have little presence on Twitter. By way of example, star player Felipe Berchesi - one of only a few squad members to play for an overseas club - hasn't tweeted since July 2013. Even then, that was his first tweet since late 2012 - but it's not all bad because at least that 2012 effort was a funny retweet.
MC Hammer would probably make a good museum security guard.— Not Will Ferrell (@itsWillyFerrell) November 12, 2012
Fair play: Berchesi aside, many members of the Uruguay team are amateurs - one member is a doctor who had to give up a job in order to play in the tournament - and this is bound to win them some affection among the underdog-loving neutrals.
In the posh seats: The team may be amateur, but with a total of 21 sponsors including main sponsor Antel and others such as Volkswagen, Gatorade and Dove, their marketing director clearly is not. Perhaps the sponsorship with the greatest resonance, however, is the long-established link with the National Meat Institute of Uruguay, through which the team will be supplied with plenty of beef.