Wales, unbeaten in pool play, were hailed by self-proclaimed underdogs Argentina as favourites for Saturday's World Cup quarter-final, but assistant coach Jonathan Thomas insisted the Welsh were unbothered by either tag.

Los Pumas, who had lost their opener to England, ensured a last-eight meeting with Wales in Marseille on Saturday after beating Japan 39-27 in their final group game.

"We know we'll be well and truly underdogs," Argentina coach Michael Cheika said of the prospect of facing a rejuventated Wales team.

Breakdown coach Thomas, who won 67 caps and featured at the 2003 and 2007 World Cups as a flanker, said head coach Warren Gatland -- in his second tenure having left in 2019 after 12 successful years at the helm -- had changed the Welsh mindset when it came to tags.

"When I was a young player with Wales, we always loved that underdog sort of feeling," he said.

"When 'Gats' came in 2008, with the evolution of the team, he changed that mindset so whether we're underdogs or favourites, it does not faze us too much whereas maybe in years gone by that was the case."

Thomas added: "We're comfortable whether we're favourites or underdogs, it doesn't bother us.

"The whole thing is a process, we need to stick to what we do well and you've got to take the emotion of being favourites or underdogs out of that.

"It's the same as the scoreboard in the game, you take the emotion out of that, stick to being in the present moment, focusing on what your job is and delivering under pressure.

"You've got to be excited about that pressure at this stage of a World Cup."

- Goal of finals rugby -

Knock out rugby, he said was "why we're here, it's what we've been building for for 3-4 months. It's been a long time".

"The whole point of sport is what's your why and what's your goal and for us as a collective our goal from day one has been to get to finals rugby, knock-out rugby.

"We've achieved that but we're not satisfied with just getting to the quarter-finals, clearly we want to win the game."

Respect for Argentina would be granted, of course, the former flanker added, warning of the quality of all teams in the last-eight.

Comparing an opening win in the Six Nations to getting out of the pool in the World Cup, Thomas said both scenarios gave you a massive confidence boost.

"When you get to this stage, any team on their day can beat anyone, they can raise their game... every team will feel like they have some momentum on their side," he said.

"Quality players, quality teams in the last eight, so it's exciting, we need to focus on ourselves and show the best version of ourselves and if we do that we've got a very good chance."

Turning to injuries to Gareth Anscombe (groin) and full-back Liam Williams (knee), Thomas said that "at this stage, it's looking positive... but we'll see".

"It's probably not as bad as first feared," he said.

"What I can confirm is that they were both running around today with the medics doing some return-to-running etc and they will try to progress that each day.

"All of those players that were injury risks, they're all in the running. The door is not closed on any of those players as it stands."

lp/pi