Australia won two of the first four World Cups contested and have lost two finals, but have been in indifferent form over the last three seasons. Wales has only reached the semifinals twice and never progressed to the final. Fiji, the long-time king of 7s rugby, is capable of producing an upset.
Here's a closer look at Pool D, which features four teams that were also grouped together in 2015:
Coach: Michael Cheika
Captain: Michael Hooper
Best RWC Performance: Champion: 1991 and '99.
Last 5 RWCs: 2015-Final, '11-3rd, '07-QF, '03-F; 1999-W.
Outlook: The Wallabies were buoyed by a 49-27 win over the All Blacks in Perth last month but demoralized a week later after losing 36-0 at Eden Park to leave the Bledisloe Cup with New Zealand for the 17th consecutive year. Perhaps a bigger loss this year was fullback Israel Folau, who had his contract terminated by Rugby Australia over contentious posts on social media comments. Kurtley Beale has stepped in as fullback and is a gifted ballplayer but has shown signs of susceptibility in the wet. Prospects for later in the tournament depend on how the scrum handles the set piece.
Players to watch: Cheika has gambled by picking just two scrumhalves — Will Genia and Nic White — in his squad. James O'Connor will feature in his second World Cup after returning to favor with Australian rugby brass after several years of off-field issues. Christian Leali'ifano, who has made a recovery from leukemia, will play at his first World Cup and is favored for the No. 10 jersey ahead of Bernard Foley.
Coach: Warren Gatland
Captain: Alun Wyn Jones
Best RWC Performance: 1987: Beat Australia in the bronze-medal playoff.
Last 5 RWCs: 2015-QF, '11-4th, '07-Group Stage, '03-QF, 1999-QF.
Outlook: The Six Nations champions are primed and ready. Wales moved to No. 1 after beating England 13-6 on Aug. 17, and after the All Blacks drew against South Africa and lost to Australia. Coach Warren Gatland didn't give the squad much chance to relax. They went to Turkey for a pre-World Cup session, following up on an earlier Swiss training camp. "Our second camp is our warm-weather camp ... putting the players through heat stress, preparing them for the conditions in Japan and we will be training about four times a day," Gatland said. The ranking has slipped following the loss to Ireland in Dublin but the fitness levels are no doubt up. Expected to reach the quarterfinals again.
Players to watch: Liam Williams is one of the top fullbacks in world rugby, while inspirational lock Wyn Jones was voted Six Nations player of the championship and is a driving force in the pack. Dan Biggar, who has played 71 tests, is the likely replacement for flyhalf Gareth Anscombe, who was forced out of the World Cup squad with an injured right knee.
Coach: John McKee
Captain: Dominiko Waqaniburotu
Best RWC Performance: Quarterfinals: 1987, 2007.
Last 5 RWCs: 2015-Group, '11-Group, '07-QF, '03-Group, 1999-QF Playoff.
Outlook: Big potential. Fiji has failed to make it out of the pool stage in the two tournaments since beating Wales and going close against eventual champion South Africa in the quarterfinals in 2007. The Fijians were forced to go through qualifying for Japan and did that by beating Samoa and Tonga in a tri-series. The good news for fans is that since placing fourth in its pool in 2015, Fiji has produced wins over France, Italy, Scotland, Japan, Canada, Georgia, Italy and Uruguay. While Fiji will be seen as a danger to Australia and Wales, it's likely they'll spar with Georgia for third place.
Players to watch: Waqaniburotu is one of five players in line for a third World Cup, along with prop Campese Ma'afu, lock Leone Nakarawa, winger Vereniki Goneva — who recently became Fiji's all-time leading test try-scorer — and fullback Kini Murimurivalu. A further 15 players could be in line for a Cup debut, including rugby league convert Semi Radradra.
Coach: Milton Haig
Captain: Merab Sharikadze
Best RWC Performance: 2015: won two pool matches (vs. Tonga, Namibia) to finish 3rd in pool and automatically qualify for 2019.
Last 5 RWCs: 2015-Group, '11-Group, '07-Group, '03-Group, 1999-DNQ.
Outlook: Georgia is appearing its fifth consecutive World Cup but has never advanced past the pool stage, although in '15 the Georgians had two wins and held the All Blacks to 43-10. This time, they'll try to go further with former England and British and Irish Lions prop and coach Graham Rowntree working with the forwards.
Rowntree has been surprised by the strength of the Georgian pack: "I honestly can't believe how strong they are across the squad," Rowntree told CNN. "The tier one nations are under incredible pressure at World Cups when they play against the likes of Georgia. The pressure's on them, and that's a real strength that we have to play to. I want us to be spoken about at this World Cup. I want to scare people."
Milton Haig, who has coached Georgia since 2012, plans to return to New Zealand after the World Cup.
Players to watch: Former captain Mamuka Gorgodze has come out of international retirement. He agreed to end a 2 1/2-year retirement after a spate of injuries and will join the team for what will be his fourth World Cup. "The squad needed him for the tournament," the Georgia Rugby Union said. Gorgodze played his 71st and last test in March 2017.
Coach: Esteban Meneses.
Captain: Juan Manuel Gaminara
Best RWC Performance: 1999: finished 3rd in pool to automatically qualify for 2003.
Last 5 RWCs: 2015-Group, '11-DNQ, '07-DNQ, '03-Group, 1999-Group.
Outlook: This is the fourth Rugby World Cup for Los Teros, who have won only twice in 11 matches. Qualified as No. 2 in the Americas after home and away wins over Canada in 2018. This season they finished second in the America's Rugby Championship, with their only defeat being against an Argentina XV. This included a notable wins over Canada at home and over the U.S. at Seattle.
Players to watch: Backrower Gaminara leads by example. Matteo Sanguinetti is an experienced prop who recently signed with Major League Rugby to play for the Houston Wildcats.