Will the Waratahs conjure a return to their glory days or will another Super Rugby title contender emerge from the Australian Conference?
Waratahs
The Waratahs topped the Australian Conference last year with just nine victories carrying them into the play-offs where they accounted for the Highlanders before being beaten by the Lions in the semi-finals.
Fly-half Bernard Foley was the star of the show with a competition-leading 223 points and the 29-year-old Wallabies playmaker has since further boosted the Tahs by putting pen to paper on a new deal with Rugby Australia.
Powerful wing Taqele Naiyaravoro was another key threat for the Tahs with 15 tries and will be a big loss having since moved north to join English side Northampton.
However, they still have plenty of talent at their disposal, including Kurtley Beale, Michael Hooper and Israel Folau, the latter having recently signed a new four-year deal with the Waratahs and Australia.
Karmichael Hunt and Adam Ashley-Cooper have also been recruited for the Tahs' latest campaign and veterans - aged 32 and 34 respectively - could form one of Super Rugby oldest and intriguing centre partnerships.
Fresh from signing his own new deal, head coach Daryl Gibson remains in charge and he has also recruited former Ospreys boss Steve Tandy as defence coach and they will work alongside Simon Cron (forwards) and Chris Whitaker (backs).
The Waratahs will also hit the road against in 2019 with three of their fixtures set to be staged at the legendary Sydney Cricket Ground.
Rebels
The Rebels were runners-up in the Australian Conference last year and finished a best-ever 9th in the overall standings but their losing record was not enough to propel them into the play-off picture.
Head coach David Wessels has since been on an impressive recruitment drive in the hope of overhauling their Conference rivals and qualifying for the business end of the competition.
He has acquired the services of former Australia international Quade Cooper on a one-year deal and the squad will be further bolstered later this year by the significant addition of current Wallabies fly-half Matt Toomua who will return to the city of his birth after finishing the Premiership season with his current club Leicester Tigers.
They will join an already talent-heavy backs division, including Will Genia, Reece Hodge and Dane Haylett-Petty that will be fancied to make the play-offs for the first time in franchise history.
The Genia-Cooper partnership famously steered the Reds to the Super Rugby title in 2011 and the Rebels are hoping for similar success.
"His biggest strength is his organisation and that's something we probably lacked a bit last year," Genia told reporters this week.
"He tells guys where they need to be, how he wants them to shape up, so I think he will make a huge difference to our team," he added.
But Wessels insists there is still work to do. "It is not about one or two star players," he said on the eve of the season, "but rather a collective squad effort and that's ultimately what we are chasing.
"We worked very hard on our recruitment...but the danger is that people think: put some talent together and you're going to get an outcome. That's not true at all," he said.
Brumbies
For the first time in six seasons, the Brumbies missed out on the playoffs last year after finishing third in the Australian Conference and 10th in the overall standings - their lowest position since 2011 and second lowest in Super Rugby history.
The Brumbies lost nine of their 16 fixtures in a taxing campaign, but eight of those defeats came within the first 11 games and they were to ultimately pay for that very poor start.
Four wins from their final five fixtures saw them make an unlikely late charge for the playoffs, but in the end they finished one win short.
They scored more tries and made more linebreaks than in 2017, kicked the ball fewer than any other side in the competition and ended a three-year drought against New Zealand sides with victory over the Hurricanes.
"The signs are there. But we have to make sure we start our season next year how we finished this year," said coach Dan McKellar.
"We understand what worked for us in the last six weeks and now we have to continue to develop that part of our game, improve our skill and hit the ground running."
Bright lights to emerge from the squad included back Tom Banks - who would go onto make his Test debut in August - second row Rory Arnold really impressed, while David Pocock was exceptional on his return.
Pete Samu looks a shrewd capture from the Crusaders, though the club missed out on re-signing Toomua. The year ahead looks to be a mightily big season for the Brumbies in the sense that 2018 may be described as a transitional year or stepping stone, but a similar performance this season will not be so readily accepted.
Reds
For the fifth year in succession, the Reds failed to make the end-of-season playoffs as they finished fourth in the Australian Conference and 13th in the overall standings.
Under Brad Thorn for the first time, major decisions were made with Quade Cooper - the club's highest-ever points scorer - exiled into club rugby and Nick Frisby - another club veteran - banished from the selection equation too.
There were a host of negatives once the season got going too: James Slipper tested positive for cocaine twice, the Reds finished with more cards than anyone in Super Rugby and suffered a humiliating and shocking 62-28 loss to the Sunwolves in Tokyo.
Yet, Thorn's youthful charges also scored more tries than in any previous year since 2011 - when they won the title - pushed both the Hurricanes and Highlanders close and dispatched of the Rebels too. Taniela Tupou and Jordan Petaia also look to be two of the most exciting talents in Australian rugby at present.
How long can Thorn keep ruling with such an iron fist if results don't substantially improve though? 2019 will be an interesting watch...
Sunwolves
Japan's Sunwolves finished bottom of the pile in the reduced 2018 format of 15 teams, off the back of finishing 18th (out of 18) and 17th (out of 18) in 2016 and 2017 respectively.
They did pick up three wins last year, which was an improvement on their two victories in 2017, but it was another desperately difficult season for Tony Brown and Jamie Joseph's charges.
Back-to-back wins over the Reds and Stormers in May was an undoubted high point, as was their defeat of the Bulls in June. But there was also 13 defeats to ponder over, many of them comprehensive.
Ahead of the 2019 season, former All Black centre Rene Ranger and Scotland fly-half Phil Burleigh have been signed from Northland and Canterbury respectively in their two marquee signings.