Gareth Davies says Wales "owe one" to South Africa in their World Cup semi-final after losing to the Springboks in the 2015 quarter-final.

The Scarlets scrum-half will win his 50th international cap in Yokohama on Sunday.

The 29-year-old was in the side beaten by Fourie du Preez's 75th-minute try at Twickenham four years ago, scoring Wales' only try in that 23-19 defeat.

"We were quite unlucky to lose that quarter-final," he said.

"It was a good bit of skill by them at the end to score a try late on. We were devastated with that because we felt we deserved to win that game.

"We feel like we owe one to them for four years ago. That will be in the back of our minds and hopefully we can get one over them this week."

That was South Africa's only victory in their five most recent encounters with Wales, who have won their past four matches against the Springboks.

South Africa head coach Rassie Erasmus played down the significance of that record when he announced his team for Sunday's semi-final, pointing to his side's change in personnel and upturn in form.

Eight players remain from last November's 20-11 loss to Wales in Cardiff, though Davies expects the seven changes from that team to pose a different challenge.

"It's a completely different team and it's full of very good individuals," Davies said.

"They've got some unbelievable talent in the backs and their forward pack is very powerful.

"There are a few key individuals in their backline we're going to have to keep our eye on to try and keep them quiet, and hopefully that will go a long way to us hopefully getting the win."

This will be Wales' third World Cup semi-final and, having lost at this stage in 1987 and 2011, they will be aiming to create history against South Africa as they bid to reach a first final.

"It's massive. I think it will be everyone's biggest game of our careers so far," Davies added.

"We've been building for a long time now, these past 18-24 months, we've really been building and the World Cup has been at the back of our minds for a long time now.

"We started the tournament pretty well with a couple of good results but we still feel like we've got another big performance in us.

"I don't think we've had one full 80-minute performance yet and we're going to have to have a good 80-minute performance to come away with an important win."