Wales have previous recent history when it comes to letting the world champions off the hook - twice.
In the space of six painful months last year, Wales blew big Millennium Stadium leads against the Springboks.
The first time it was a 13-point advantage that world champions South Africa wiped out and won 34-31, and then they fought back from 11 points behind to claim a 29-25 triumph.
The architect of that latter victory was fly-half marksman Morne Steyn, whose 19-point haul included five penalties and left Wales bewildered how everything had unravelled so spectacularly.
Steyn had previously displayed his relentless accuracy against the 2009 British and Irish Lions - a touring Test team which included several current Wales players - and Cardiff Blues lock Davies knows discipline will be paramount.
"You don't want to give away any easy points," said the 24-year-old. "We've talked all week about not giving silly penalties away.
"The last time we played against them we gave away too many soft penalties, which meant when we were out in front they had chances to claw back.
"The challenge for us now is not to give those soft penalties away, and to finish the game with a win."
Davies' sentiments were echoed by Wales assistant coach Rob Howley, who added: "Morne Steyn is a wonderful kicker.
"You don't want to be giving him any easy points. He is one of the world-class kickers in the game at this moment in time.
"He has got great composure and accuracy. We want to keep our discipline, first and foremost.
"In a World Cup it is about winning and gaining momentum. All we are looking ahead at is the game on Sunday, which is so important to us.
"It's about making sure we play in the right areas. Some of our players have played against South Africa eight times over the last three or four years, including their Lions experiences in 2009.
"The players have learnt, and that is what Test match rugby is about."
Wales coach Warren Gatland is due to announce his starting line-up on Friday for a game that will put the winners in pole position to claim Pool D's top spot.
One internet poll currently has Sunday's clash as the game most likely to cause a pool stage upset, which says everything about Wales' impressive pre-tournament form that netted victories over England and Argentina.
"Personally, I think it's great that we get to start with a big one, to start with a bang," said Davies.
"It sends the message out to the rest that we are up for it.
"They are a world-class team. We have played them enough times to know what to expect, and we are under no illusions how tough this game is going to be."
Howley, meanwhile, has conceded that Stephen Jones is a doubt for the Springboks encounter.
The Scarlets fly-half has not played since pulling out during the warm-up before Wales' opening World Cup preparation game against England at Twickenham just over four weeks ago.
Jones, who needs one more appearance to break Gareth Thomas' Wales cap record of 100, is battling with James Hook for the number 10 shirt.
"Steve has continued to do his rehab," said Howley, of Jones' calf muscle injury.
"He hasn't taken a full part in training as of yet, and hopefully he will take a full part probably tomorrow.
"At this moment, obviously there is a doubt.
"He hasn't played for a long period of time. We need to give Steve enough time to make sure he is right. We are giving him plenty of time."
The Springboks will continue to monitor lock Bakkies Botha, who has an Achilles' issue that could threaten his involvement at Wellington Regional Stadium. Danie Rossouw would be Botha's probable replacement.
"Bakkies is a person you always miss - in his special way - but for us it's important to keep the routine of the team going," said Springboks number eight Pierre Spies.
"I think we will have Danie Rossouw coming in if Bakkies is not ready, and Danie is also an exceptional player.
"We will wait and see how the week turns out, and hopefully he can recover in time."
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