Tokyo - Cardiff Blues winger Owen Lane will arrive in Japan Tuesday as a surprise replacement for injured No 8 Josh Navidi ahead of Sunday's World Cup semi-final against South Africa, the Welsh Rugby Union said.

Navidi sustained a grade two hamstring tear in the gripping 20-19 quarter-final win over France.

With five of the six named backrowers still fit, coach Warren Gatland warned Monday the replacement for Navidi would be a back.

And the WRU confirmed in a tweet that Lane was en route for Japan.

"He's a great character, he's obviously a very good player and has huge potential going forward," Wales defence coach Shaun Edwards said of Lane.

"We were very impressed with him in the summer. We've been away for quite a few weeks now and he's got some great banter as well. Sometimes you need that after you've been away from home for so long!"

Edwards said the team had been sad to see Navidi ruled out.

"Josh has been one of our go-to players over the last two years, through a period when we've been successful," he said.

"Everyone's gutted for Josh... he's one of our best defensive players, so someone will have to step up into his position."

Centre Jonathan Davies is nursing a knee injury that saw him ruled out of the France game an hour before kick-off and midfield partner Hadleigh Parkes played with a shoulder contusion and a bone fracture in his hand.

Davies is expected to be fit and available for Sunday's semi against the Springboks, but should one centre break down, it is likely winger George North would be considered as cover given that Lane is an out-and-out winger.

"We all want our best players fit," said Edwards.

"Obviously the Fijian guy from France (Virimi Vakatawa) was a thorn in our side last week.

"You want your more experienced guys for the big games, particularly for Jon Davies because he missed the last World Cup.

"He's had some serious injuries over the years, but I'm pretty sure he'll be ready for the weekend."