DRAGONS number eight Ross Moriarty is relishing a confrontation with South Africa's bruisers, declaring that he thrives when the going gets tough.

Wales take on the Springboks in Yokohama on Sunday (kick-off 9am) with the prize for success being a first ever World Cup final.

Moriarty is likely to be promoted from his role of impact sub courtesy of Josh Navidi's tournament-ending hamstring injury and will be in the thick of it against a hefty South African pack.

The Boks secured their place in the semi-finals by overpowering hosts Japan with a pack that weighed in at 900kg.

Moriarty has faced South Africa three times and has a perfect record of three victories, albeit last autumn he lasted just 11 minutes after suffering a concussion.

South Wales Argus:

The 25-year-old believes going toe-to-toe with big units suits his abrasive style.

"This is a game I look forward to. I know what their forwards thrive on, which is being physical, and that's what I thrive on as well," said the back rower, who will win his 40th cap.

"Some players go hiding when it gets tough, but I think I get better in those situations."

"We all know the All Blacks are very physical, but South Africa are renowned for being a physical team too," he continued.

"They've got some very good backs, so we know what we're going to have to do to keep them at bay. That's what we'll be looking at."

Wales have won all four Tests since losing to South Africa in the quarter-finals of the last World Cup but the Boks are resurgent under former Munster boss Rassie Erasmus.

Warren Gatland's men will have to produce their best display of the tournament to earn a semi-final showdown with either England or New Zealand.

South Wales Argus:

"It's going to be a very big challenge. We've had some good results against them in the autumn internationals in the last few years," said Moriarty.

"We know what South Africa are capable of and we know what we're going to have to do in training and in our analysis work to put that out on the field on Sunday.

"Everyone is obviously excited. This is what we've been training for over the last however many years and is what it has all come down to. We're looking forward to playing South Africa."

Moriarty won his third and fourth caps at England 2015 but was behind Sam Warburton, Taulupe Faletau, Justin Tipuric, Dan Lydiate and James King in the pecking order.

Now he is a central figure as Wales attempt to secure a place in the final a week on Saturday rather than the third/fourth play-off 24 hours earlier.

South Wales Argus:

"It’s all come quite quickly. We all know rugby is quite a short career, but it’s going very fast now," said the back rower, who swapped Gloucester for the Dragons in the summer of 2018.

“I’m 26 next year. To be involved in a game like this at the weekend is what I started playing the game for even if I didn’t think much about it when I was younger. This is what we train for."

Gatland names his team on Friday with Moriarty in pole position to slot in next to Aaron Wainwright and Justin Tipuric in the back row.

That would leave the Scarlets flankers Aaron Shingler and James Davies, the former a blindside and latter an openside, tussling for the role of impact sub.