Ireland captain Dan Sheehan says he has "full confidence" in his team-mates as he dismissed talk of a decline in Irish rugby as "nonsense".

Andy Farrell's side sit third in the world rankings, but a string of double-digit losses to South Africa, New Zealand and France have raised question marks about the team's trajectory.

Farrell this week admitted his team are not yet ready to have realistic ambitions of winning next year's World Cup in Australia.

But before facing Argentina, Fiji and world champions South Africa at home in this month's Nations Championship fixtures, Sheehan insisted Ireland must "fully back ourselves".

"I've full confidence in this group," said Sheehan, who is again deputising for injured skipper Caelan Doris this month.

"I think reminding myself and the group of the quality we have...sometimes you can hear outside noise about, 'is this a transitioning time for Irish rugby?' or 'is this a decline in Irish rugby?' and I think it's all nonsense really.

"Making sure we keep our confidence in what we have, in the personnel we have, the coaches we have in the group, it's all set up perfectly for us. I think it's just doubling down on our work ethic and making sure we fully back ourselves."

Ireland have won six out of their eight Tests this year, including convincing wins over England and Scotland that helped seal the Six Nations Triple Crown.

However, a 36-14 loss to France in Paris and July's 40-21 reverse to the All Blacks exposed the shortcomings in Farrell's side, with Sheehan admitting improvement is needed "across a lot of areas".

"We've been disappointed with a fair few performances that we've had, especially the big opportunities we had over the summer," added the 28-year-old Leinster hooker.

"The Australia game, I know we scraped a win but it probably wasn't a performance we wanted. And the same with Eden Park [against New Zealand], I think we were beaten by about 20.

"Obviously, set-piece is something we need to continue to drive. I think we have the ability in the group. You see it in the provinces, it's a quality set-piece we have and we need to make sure we drive that at international level but there's plenty."

Sheehan added that while Ireland have a "few things to tidy up", he does not feel the side are a "million miles off" where they need to be.

"I thought the focus over the last two weeks has been great – honest feedback, honest conversations with each other about where we're at and where we need to be.

"I think we can all feel we have the talent in the group, and we're going in the right direction if we can put all of our minds together."

Sheehan also expects a tough opening assignment against Argentina on Friday night as the Pumas chase a first away win over Ireland at the 12th attempt - having beaten Farrell's British and Irish Lions at the Aviva Stadium last year.

"All eyes will be on this game and they're a top-quality side that put the Lions away here so we know the threat they have, the passion they have for the game as well," said Sheehan.

"I'm sure they'll be coming out all guns blazing and we need to match that and take it to a different level."