Warren Gatland says his Wales players are fully aware they can achieve "something special" against South Africa on Saturday.
Wales have won four of the last five encounters with the Springboks, and they are also chasing a ninth successive triumph against all opponents, which would equal their longest unbeaten run since 1999.
And they go into the Principality Stadium clash needing victory to complete a first four-from-four autumn Tests clean sweep after seeing off Scotland, Australia and Tonga earlier this month.
"What has built nicely is the momentum," said Wales head coach Gatland, who has replaced unavailable full-back Leigh Halfpenny with Liam Williams for the Springboks encounter.
"The players are fully aware of what they've achieved and they can do something special, and from that they know the momentum is created for the Six Nations and they can continue to build towards the World Cup.
"The way the players have trained at the moment, I haven't seen this level of maturity in a group of players. Our composure in games has been outstanding.
"Even last week (against Tonga) we found ourselves in a bit of a hole and managed to work our way out of it. In the past, that has compounded us.
TEAM NEWS 🏴 @SanjayWills starts at fullback against @Springboks in the only change to the starting XV that beat Australia.
🔴 Mae Warren Gatland eisiau gorffen yr ymgyrch gyda perfformiad mawr yn erbyn De Affrica. #HWFN pic.twitter.com/wvxoSZqoZM
— Welsh Rugby Union 🏉 (@WelshRugbyUnion) November 22, 2018
"But there is some real maturity in this group, and they are calm. You can see they are motivated as well."
Halfpenny misses the Springboks game due to the concussion he suffered during Wales' 9-6 victory against Australia 12 days ago, with Williams taking over as a solitary change from that match.
Halfpenny went off near the end of the Australia fixture after being clattered by a challenge from Wallabies centre Samu Kerevi, who escaped sanction.
Williams, who lined up on the wing and scored two tries when Wales beat Tonga 74-24 five days ago, started twice at full-back for his country last season and in all three 2017 British and Irish Lions Tests against New Zealand.
Gareth Anscombe will fill the fly-half berth, with Dan Biggar on replacement duty, while Adam Beard is again captain Alun Wyn Jones' second-row partner.
Elsewhere, wing George North has recovered from a leg injury that forced him off against the Wallabies and Gatland retains a back row of Dan Lydiate, Justin Tipuric and Ross Moriarty.
South Africa have won plaudits for their vastly improved performances under head coach Rassie Erasmus, who was only appointed to the role eight months ago.
This time last year, the Springboks suffered a 38-3 drubbing against Ireland before ending their European tour by losing to Wales, but 2018 has seen a notable revival with victories over world champions New Zealand, England (twice), Australia, France and Scotland.
Gatland added: "They have reclaimed some of their old identity and what they are about.
"Physicality and a strong scrum, a driving lineout and strong ball-carriers. That's why you always respect them for what they are.
"They have gone back to being tough and physical and have subtleties in the way they play. (Handre) Pollard runs more than most 10s in world rugby from set-piece.
"They have some very sharp wingers who can finish, and a forward pack that can compete hard on the ball.
"We are expecting a very tough, physical encounter, and the players are excited about it.
"It's the end of a campaign, like a cup game. Winner takes all."
