Ireland head coach Andy Farrell lauded Ross Byrne's "nerves of steel" after the substitute kicked a dramatic late penalty to sink Australia in Dublin.

The 27-year-old was winning his first cap since March last year.

"He has nerves of steel," Farrell told Amazon Prime.

"He deserves everything he gets as far as plaudits are concerned. It takes guts, doesn't it, to back yourself and go for it.

"He was never in doubt. He actually took the kick pretty quickly but I am absolutely delighted for him."

Byrne, a late addition to the Ireland squad during the week as a replacement for the injured Joey Carbery, was not originally named in Farrell's 23-man panel for the last of their three autumn internationals.

However, captain Johnny Sexton, who himself missed the win over Fiji last week because of a dead leg, had to drop out of the team just minutes before Saturday's victory over the Aussies after picking up a calf strain.

That meant 22-year-old fly-half Jack Crowley was drafted into the starting line-up at the last minute, with Byrne taking his place on the bench before replacing him in the second half.

Farrell also had special praise for Munster's Crowley, who kicked the only penalty of the first half in what was just just his third senior Ireland appearance.

"That was such a big win for us as a squad," the head coach continued.

"Nobody likes to lose their captain just before the game but it is great for us going forward, finding out about ourselves as a group.

"Jack coming in - what a five or six weeks it has been for him. [Playing for] Emerging Ireland and then he finds himself on the bench, and his debut and then finds himself starting.

"The group looked after him, they looked after Joe [McCarthy, who came on for his debut against Australia] as well and I thought Craig Casey did well when he came on.

"It is awesome in this window to find out more about the group and push forward on to the Six Nations."

'Good sides find a way to win'

Saturday evening's win over the Wallabies, which completed a hat-trick of autumn victories for the world's number-one-ranked side, was a tense and cagey affair.

Substitute Bundee Aki, returning from suspension, scored a converted try that was cancelled out by Jordan Petaia going over before Byrne's decisive set-piece.

Farrell accepted it was not the prettiest of performances but was pleased with how his side persisted until securing a victory.

"You find out on days like these. We've had a bit of illness going through the squad and fatigue as well, even though we've only played three games.

"But there's been no excuses, like when your captain goes down. It's good for us as a group because it shows us where we're at.

"We weren't at our best and Australia deserve credit for that but when things aren't quite going your way, good sides try to find a way. We found a bit of luck but we came out on the right side and we roll onto the Six Nations."