Iain Henderson believes Ireland's clash with Argentina this weekend could be their toughest fixture of the November series.
Joe Schmidt has named a strong starting XV for the tie, with winger Adam Byrne making his debut, while James Ryan earns his first Test start in the second-row.
The Pumas are coming into this game on the back of a comprehensive victory over Italy last weekend, and Henderson is well aware that Argentina will want to round off their season with another win on Saturday.
Speaking to RTÉ Sport, the Ulster player said: "They're off the back of a run of a couple of losses, they got a good win over Italy and to beat Italy over there - a lot of people mightn't think it sounds like much but that's good for them to break the losing streak they were having.
"They're not going to come over this weekend, looking to slip back into their losing streak, they're going to want to continue that winning streak.
"The Argentinians are off the back of a long season too but they're going to be looking on finishing their whole season on beating Ireland in Dublin and that's something we're going to have to deal with them throwing at us.
"Equally, we're going to have to step up to the challenge again."
Ireland are also approaching this game with some winning momentum behind them. A comfortable win over South Africa in their November Test opener was followed by a tougher assignment against Fiji, where a much-changed side came away with a marginal three-point win.
Schmidt's squad appear to be reaching the right tempo in preparation for the arrival of Argentina, with Henderson reporting that training 'got a bit feisty' on Thursday afternoon.
But after coming through some challenging Tests already in this series, Henderson suspects that the toughest assignment could be still awaiting them.
"We knew they were going to be three big tests. Obviously with South Africa, we went out and did the job, we came out and worked hard for each other.
"That's what we knew we had to do. In the back of our minds, we always knew that Fiji and Argentina were going to be equally as tough if not tougher because after you take out two big Test games, there's a lot of sore bodies, a lot of people carrying niggles."
On the provincial front, Henderson will be joined by a new teammate in the new year after Ulster announced that Ireland international tighthead prop Marty Moore will join the province next summer on a two-year deal.
Moore, who made his international bow in 2014, missed out on last year's Six Nations campaign due to injury, and has not been selected for Ireland since subsequently moving to Wasps.
Henderson says he is looking forward to linking up with his old international teammate again, and is interested to see how Moore progresses upon his return.
"Marty has gone over there and has been good for them (Wasps), he's locked down a good few scrums for them.
"I think he's of a time where he wants to come back and look at maybe nosing his way into the Irish set-up. Since he's been away, Tadhg (Furlong) obviously has excelled with Leinster. I think he'll be looking forward to getting his name back in the mixer.
"I think we'll be happy to promote some more competition among the props in Ulster and that's really interesting.
"I obviously played with Marty, not only in Ireland but at underage as well so looking forward to getting him back."
Live coverage of Ireland v Argentina begins on Saturday on RTÉ 2 television and RTÉ Player at 4.30. Live commentary is on RTÉ Radio 1’s Saturday Sport, which starts at 2.45, and you can follow all of the build-up and action on our live blog online at rte.ie/sport and on the News Now app.