Cardiff - Wales coach Rob Howley fears his side will face a "wounded animal" when South Africa arrive in Cardiff.
While Wales scraped to a thoroughly unconvincing and barely-deserved 33-30 win at home to Japan on Saturday, next opponents South Africa suffered a maiden loss to Italy as they went down 20-18 in Florence.
Now Wales and South Africa will both be desperate for a win to appease their critics when they meet at the Principality Stadium on November 26, in a repeat of last year's World Cup quarter-final that the Springboks edged 23-19 at Twickenham.
"We have to look our game and look at South Africa's strengths and weaknesses but we know what to expect after playing them so many times in recent years," said Howley.
"We won 12-6 the last time we played them in Cardiff (in 2014) and that will give our players confidence.
"There will be plenty of players on both sides next week who were involved in that game two years ago and know that we have beaten them."
Former Wales scrumhalf Howley, himself now under pressure as he takes charge in the absence on Lions duty of Warren Gatland, added: "But it is a wounded animal that is coming to the Principality Stadium next week after their losses.
"It was a great win for Italy but the weather conditions were not great in Florence and under the roof here in Cardiff, it will be a far different game next week."
Wales know they must improve on this display if they are to record only a third win over the Springboks, not least in defence.
Dan Lydiate and Jamie Roberts both scored tries in the first half and captain Sam Warburton followed suit early in the second period.
But victory came down to 15 points from the boot of Leigh Halfpenny and a last-gasp drop goal by young replacement flyhalf Sam Davies, eight seconds from time, to cinch victory over a new-look Japan side.
"The feeling is more of relief than frustration, I thought Japan were the better team and deserved to win," said Warburton.
"We used our get out of jail free card, and Sam Davies showed composure at the end. The players are all disappointed and it felt like a defeat in the changing room after the game.
"They came at us with the ball in hand and we couldn't get out of our own half in the second half.
"People will look back and call it a win and it provides food for thought next week. When we've made changes in the autumn before, we've sometimes come up with that kind of performance.
"We want to encourage an offloading game. When you win the collision, you earn the right to offload and we probably didn't do that today.
"Japan's kicking game put us under pressure because we lost the aerial battle. But we fuelled Japan's enthusiasm and energy and their counter-attack with turn-overs that gifted them 14 points.
"It's a concern to concede another 30 points, especially as many of them were from our own mistakes when we had the ball."
Akihito Yamade and Kenki Fukuoka crossed before Amanaki Lotoahea's try in the 73rd minute allowed Yu Tamura to level the scores late on.
Reflecting on his team's gutsy performance, Japan coach Jamie Joseph said: "I think we surprised Wales and their fans how we played the game.
"A fair result would have been a draw, and the players are disappointed to have come up short," added the former New Zealand international.