Sexton suffered a dead leg in the victory over South Africa earlier this month and did not feature in last weekend's 35-17 triumph over Fiji.

But the fly-half returns to the team for the match against Australia in one of seven alterations from that Fiji win, as the likes of Hugo Keenan, Josh van der Flier and Peter O'Mahony start.

Andrew Porter and Dan Sheehan return to the front row, while James Ryan comes into the second row.

Ireland will be without Joey Carbery and Robbie Henshaw, who both miss out through injury.

Australia is hoping to bounce back from its first ever defeat to Italy last weekend, from which just four starters remain.

Mark Nawaqanitawase and Tom Wright stay on the wings, but James Slipper returns to captain in what will be his 126th Test.

Andrew Kellaway starts at fullback, as Dave Rennie opts to keep the centre pairing of Hunter Paisami and Len Ikitau, while Allan Alaalatoa continues in the front row.

Ireland team: Hugo Keenan, Mack Hansen, Garry Ringrose, Stuart McCloskey, Jimmy O'Brien, Jonny Sexton (captain), Jamison Gibson Park; Andrew Porter, Dan Sheehan, Tadhg Furlong, Tadhg Beirne, James Ryan, Peter O'Mahony, Josh van der Flier, Caelan Doris.

Replacements: Rob Herring, Cian Healy, Finlay Bealham, Joe McCarthy, Jack Conan, Craig Casey, Jack Crowley, Bundee Aki.

Australia team: Andrew Kellaway, Mark Nawaqanitawase, Len Ikitau, Hunter Paisami, Tom Wright, Bernard Foley, Nic White; James Slipper (captain), David Porecki, Allan Alaalatoa, Nick Frost, Cadeyrn Neville, Jed Holloway, Michael Hooper, Rob Valentini.

Replacements: Folau Fainga'a, Tom Robertson, Taniela Tupou, Will Skelton, Pete Samu, Jake Gordon, Noah Lolesio, Jordan Petaia.