Tadhg Beirne said Friday it was a "special, special moment" to be captaining Ireland after being handed the armband to lead the team out for the first time against Japan.
The Munster lock has been capped 71 times and assumed the responsibility mid-way through a test before, but has never started as skipper.
That will change on Saturday in Newcastle, north of Sydney, when Ireland face Eddie Jones's Japan in the Nations Championship after coach Andy Farrell rested Dan Sheehan.
Sheehan stood in for usual skipper Caelan Doris, who is injured and not in Australia, in their 33-31 win over the Wallabies last week in Sydney.
"A huge honour. Of course it is," said Beirne. "I've had the honour of being captain on field when our main guys haven't been there – Dan and Caelan.
"But to lead the guys out from the start, again I revert to that word 'special', because it is a special, special moment for me and my family."
Ireland head into the game with lessons learned from Sydney, where they came from behind four times after Australia burst out of the blocks and put them on the back foot
"There's a lot of positives, obviously," said Beirne.
"The fight from everyone to stay in it and come from behind was really pleasing. But I think there's a lot of areas of the game where we probably weren't particularly happy with the way we did things.
"Our defence wasn't where it needed to be physically, and credit to the Aussies – they played incredibly well."
Japan have only beaten Ireland once in 11 meetings but their confidence high after toppling Italy 27-10 in Tokyo last week to open their Nations Championship with a bang.
Beirne said they were preparing for a fast-paced game.
"They play fast rugby. I've played them in the past they they like to keep the tempo of the game up," he said. "It's on us to match that.
"But especially physically, I think that's going to be a big area of the game where we're going to have to put a stamp on it."