Joe Schmidt explains why he selected Garry Ringrose and Iain Henderson to face Australia

Four changes but each one justified and each man ready, according to Joe Schmidt.

Australia are in town this weekend and Ireland have another must-win game. Schmidt made four changes to the team that lost 21-9 to New Zealand last week and injury played a part, he said, in all four. At Carton House this afternoon, the Kiwi offered the key reasons for many of his selection calls. He said:

"Iain Henderson was fresh. Donnacha Ryan has put in a huge shift. He's played in all three games so far. He was pretty fatigued after the most recent Test"

Garry Ringrose continues at inside centre, a role he admitted on Saturday that he was unaccustomed to. Addressing his backline tweaks, Schmidt said:

"Garry Ringrose, he gets to play inside Jared Payne. It's another learning experience and another real experience to step up against Reece Hodge and Tevita Kuridrani. It's a massive ask for him, they're both very big men as well as starting to develop real experience - Hodge and Tevita Kuridrani has obviously got that. "With Keith Earls, Simon Zebo was very sore after the game. He's taken  two or three days. He trained today, but probably didn't train flat out. He's still got 48 hours to fully recover and we're hopeful he'll be 100% by Saturday.  "With that bit of lingering doubt, Keith brings a freshness to the group and hopefully that will add a bit of vitality. Keith's roundly experience and also gives us a bit of midfield cover should we need it. That versatility is not too bad to have either. "Rob trained for the first time today. We just trained him away quietly because that's how you progress them back. He's still got another 48 hours to really build himself into this weekend's match. Same with CJ Stander."

Kick-off at the Aviva Stadium is 5:30pm this Saturday. Dick Clerkin makes his GAA Hour debut to talk about a wonderful career and argue passionately with Colm Parkinson over Sky Sports GAA. Subscribe here on iTunes.