Ross Byrne has been called into the Ireland squad ahead of Saturday's game against Australia as doubts persist over Johnny Sexton’s fitness.Leinster out-half Byrne linked up with the squad on Monday night to boost Andy Farrell’s options at 10.Sexton is still struggling with the dead leg he suffered against South Africa while Joey Carbery has been ruled out of the Wallabies game after sustaining a head injury against Fiji.Byrne’s Leinster team-mate Ciarán Frawley had jumped ahead of him in the Ireland pecking order but he will undergo knee surgery on Tuesday, which will sideline him for a number of months.Byrne won the last of his 14 Ireland caps as a replacement in the Six Nations win over England in 2021.Munster No 10 Jack Crowley came off the bench for his Ireland debut against Fiji and he could again feature against Australia as Farrell’s side bid to end their year with a record-equalling 12th successive home win.Robbie Henshaw has been ruled out with a hamstring injury while James Ryan, Andrew Porter, Josh van der Flier and Hugo Keenan are all carrying knocks.ℹ️ The latest from Ireland camp. #TeamOfUs | #IREvAUS pic.twitter.com/pz0in2dxYsFollow a live blog of Ireland v Australia on RTÉ.ie/sport and RTÉ News app this Saturday from 8pm with live radio commentary on RTÉ Radio 1.