Neil Jenkins has stressed how Wales must be "on the ball and on the money" when they target World Cup quarter-final glory against South Africa at Twickenham.

Saturday's opening last-eight clash offers Wales an opportunity of matching their World Cup achievement in New Zealand four years ago, when they were semi-finalists for the first time since 1987.

Wales lost 16 successive Tests against the Springboks before beating them the last time the countries clashed in November 2014.

Their only previous win came in 1999, when Jenkins played in the newly-opened Millennium Stadium's first international and helped his team claim a 29-19 success.

"We have come close an awful lot of times," Wales skills coach Jenkins said.

"We won in November against them, and we should have won in Nelspruit in that second Test last year, but we threw it away after being 30-17 up with eight or nine minutes to go and lost. It was quite hard to take.

"It just shows that when you play against any of the top sides in the world you have got to play for the full 80 minutes. You can't switch off at any time - you have to constantly be on the ball and on the money.

"If we bring our A game tomorrow, which we hope we will do, I am sure it will be a fantastic game. There is no doubt it could go either way.

"South Africa are a fantastic rugby side. They have gone through the gears quickly (since suffering a shock defeat to Japan in their Pool B opener) and shown what they are all about. They are a world-class side across the board.

"The focus for us is to bring our A game and play like we can play, implementing our own game-plan and seeing where it takes us. I am sure it will be a very tightly-contested Test match."

One area where Wales will need to improve considerably is in terms of an attacking edge, having failed to capitalise on a temporary two-man advantage during last Saturday's Pool A decider against Australia that ultimately went the Wallabies' way 15-6.

"Without doubt, we should have scored a try in that period," Jenkins added. "You have to come away with points against 13 men.

"We have been through certain scenarios. There were overlaps that were clear, and we didn't make the right decisions. I think if we are in a similar position tomorrow, we will put that to bed."

For Wales full-back Gareth Anscombe, the quarter-final continues an eventful journey of the past few months.

Having appeared on course to make Wales' 31-man World Cup squad in August, he then suffered an injury during training that put him out of contention.

But along with James Hook, he subsequently gained a call-up from Wales head coach Warren Gatland after Scott Williams and Hallam Amos suffered tournament-ending injuries during last month's win against England.

"When I got the injury in training, it was pretty unfortunate, and when we looked at my rehab time we thought it would be about a month," Anscombe said.

"Obviously, with the injuries we've had it gave me a chance, and now to be here starting a big quarter-final, it's a dream come true.

"It is a special moment for me - my family are all here - and for the team.

"We really want to progress through this tournament. We feel we are good enough to, and we certainly think we can win tomorrow. It's a huge occasion that every rugby player would love to be in, so I feel very privileged and cannot wait.

"We got out of a tough pool and into the quarter-finals. None of us want to go home yet."

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