Ireland may be without their first-choice 10-12 axis but Paddy Jackson and Garry Ringrose must produce “top" performances, says assistant coach Andy Farrell.

Johnny Sexton (66 caps) and Robbie Henshaw (24 caps) are both missing for the Test against Australia tomorrow (5.30pm, live on RTÉ Radio 1 and RTÉ2) after sustaining injuries during last week’s defeat to New Zealand.

In come 18-cap Ulster fly-half Jackson, who has been favoured, in Sexton’s absence, since the summer tour to South Africa, and 21-year-old Leinster centre Ringrose, who will win his third cap.

“They are top professionals,” Farrell told RTÉ Sport.

“They are aware of what they need to do, not just defensively but attacking-wise.

“They’ve both got big jobs to do and their preparation has been unbelievably thorough.

“If their preparation is thorough, that breeds confidence, not just within themselves but within the team.

“Those guys have come in this week and slotted in seamlessly and we’re expecting a top performance from them both.”

The historic win over New Zealand means that no matter what happens tomorrow, the series will be seen as a success, with the Chicago victory ending a 28-Test, 111-year hoodoo. 

However, Farrell added that Joe Schmidt's side can draw inspiration from a number of different areas for the Lansdowne Road clash. 

"There are all sorts that we can draw emotion from," he said.

"Rory [Best's] 100th cap; Mick Kearney, our manager, is stepping down after this; the world rankings; beating the three southern hemisphere sides etc. 

"There's a lot that we can cling on to but we're a process-driven team that's all about getting our detail right and living in the moment and it won't be any different tomorrow." 

Watch Ireland v Australia (kick-off 5.30pm) live on RTÉ2, listen live on Radio 1's Saturday Sport and follow RTÉ Sport Online's live blog