Comment: World Cup planning at the forefront of Joe Schmidt’s mind as Kiwi rolls the dice for decisive Test
As Ireland arrive at the final game of what has been a long season, Joe Schmidt was never likely to have a full deck to pick from, but there are merits to the head coach having his hand somewhat forced.
For all of the opportunities that still lie ahead before next year's World Cup, few will compare to having a Test series on the line in the southern hemisphere.
Should Ireland get the job done tomorrow, it would cap what has been the most successful season in this country's history. That said, win, lose, or draw, when you consider the fringe players who have gotten valuable game time in a pressurised environment, this month's tour has been a relative success.
Injuries have reduced Schmidt's options, yet the Kiwi hasn't been shy in making some big calls, and he stayed true to his word in wanting to give all 32 players game-time in Australia. Should Ross Byrne come off the bench, he will complete the set, and while it would have been easy to select Joey Carbery, Byrne wasn't picked for the tour to make up the numbers.
By making five changes, the Ireland team looks suitably fresh, which has left certain players and combinations eager to stake their claim one last time this season.
At the start of the month, hooker looked like one of the few positions that Ireland needed to strengthen, but the landscape has improved drastically over recent weeks.
By missing out on the tour entirely, Rory Best was the biggest loser, but up to now, Seán Cronin hasn't been far behind him. The Leinster hooker would have looked at this series, not only as a chance to cement himself as Ireland's second-choice, but, more importantly, a chance to close the gap on Best.
Cronin has had to bide his time after what must have been a frustrating couple of weeks, but he gets his opportunity to prove a point to Schmidt. All the while Cronin watched on from the stands last week, he did so as Niall Scannell further enhanced his growing reputation, while Rob Herring has also enjoyed a fine tour. At yesterday's press conference, Schmidt very publicly laid down the challenge to Cronin when he said: "We'd love to see him do really well in the set-pieces."
Still irked by that scrum penalty concession in the first Test defeat, Cronin has had to shoulder the blame. Question marks over whether or not that was his fault remain, but one thing is for sure, Cronin won't get a better opportunity to remind Schmidt just what he is capable of.
The more games Garry Ringrose misses for Ireland, his importance becomes even clearer.
Ringrose is a special talent but his injury profile is growing and come the World Cup, Ireland need players who can seamlessly slot into different combinations.
During their time together at Connacht, Robbie Henshaw and Bundee Aki proved that they are a midfield force, yet they didn't fire on all cylinders in Brisbane.
Henshaw's rustiness at outside centre was understandable given his lack of game-time there. He will be mindful however, that the Wallabies will again look to target Ireland in midfield.
In Aki's case, Schmidt will want to see more of him in attack. The Connacht player has more to his game than just trucking it up through the middle, and nothing typified that more than Aki's role in CJ Stander's stunning try at Twickenham earlier this year.
Playing with Connacht, Aki has the freedom to express himself and seeing more of that flair coupled with the hard edge that he invariably brings, would help solidify Ireland's midfield, while also making it an attacking threat.
Is O'Mahony a realistic openside option?
You have to go back to the 2012 Six Nations to find the last time Peter O'Mahony started at openside flanker for Ireland. Had Seán O'Brien, Dan Leavy, Josh van der Flier or Rhys Ruddock been fit, O'Mahony wouldn't have found himself at the opposite side of the scrum - that he does is a testament to his form.
Schmidt wanting to start Jack Conan at No 8 is understandable, yet many would have expected Jordi Murphy to wear No 7. O'Mahony, however, has captained the team well and has been excellent in both games. His work at the breakdown last weekend was superb and something similar will be expected tomorrow.
Given the calibre of more natural opensides that Ireland are missing, O'Mahony probably won't be in this position too often, but Schmidt is preparing for a potential injury crisis a la the 2015 World Cup, which is exactly the kind of forward planning that Ireland need.