The match, which will be played at the Vale Resort outside Cardiff at 18h00 (SA time), marks his last chance to test player combinations before finalising the World Rugby U20 Championship squad.
Roux made four changes and two positional switches to the side than ran on against England in Coventry on Friday, with fullback Andrew Kota, scrumhalf Sanele Nohamba, flanker Evan Roos and prop Kudzwai Dube earning starts.
Kota’s inclusion at No15 sees Thaakir Abrahams move to the right wing, while Marnus Potgieter switches from the wing to centre where he will join forces with Rikus Pretorius in the midfield.
Flanker Phendulani Buthelezi will lead the team, which features an expanded replacements bench featuring 10 players.
“We have tried to give everyone a chance to play on tour so that we can see where we are at this stage,” said Roux.
“There are another five or six players at home that we are also still looking at, so this is a good opportunity for everyone.”
Of Wales, the coach said: “They are a very good side from what we have seen in the U20 Six Nations and they are well-coached. They defeated England in the competition and could easily have finished second on the log.
“So this is going to be a good game and great test for the players, especially given the demanding schedule that we specifically planned for them on this tour.”
Commenting on what he wanted to see from his team in their final international friendly before the World Rugby U20 Championship in Argentina in June and said: “We would like to see how long the players can hang in the game. We trailed England by five points with eight minutes to go in our last game, and the outcome could have been very different.
“That said, we have tried to make this tour as tough as possible for the players. We flew to the UK on Tuesday, trained every day, didn’t give them off, and we have had double training sessions as well because we felt that it would not benefit them in Argentina to rest before these matches.
“So the main thing on this tour was to prepare them mentally for the World Rugby U20 Championship by making things as tough as possible.
“Hopefully we can beat Wales with players who have had a more physically-demanding schedule, but the main thing I would like to see how long the legs can last in this game.”
The Junior Springboks will face Scotland (4 June), Georgia (8 June) and New Zealand (12 June) in the pool stages of the World Rugby U20 Championship, with the team set to depart for Rosario exactly a month from today.
Roux will announce his 28-man World Rugby U20 Championship squad early in May.
Junior Springbok team to face Wales:
15 – Andrew Kota (Vodacom Blue Bulls)
14 – Thaakir Abrahams (Cell C Sharks)
13 – Marnus Potgieter (Vodacom Blue Bulls)
12 – Rikus Pretorius (DHL Western Province)
11 – Caleb Dingaan (Cell C Sharks)
10 – Boeta Chamberlain (Cell C Sharks)
9 – Sanele Nohamba (Cell C Sharks)
8 – Francke Horn (DHL Western Province)
7 – Phendulani Buthelezi (captain – Cell C Sharks)
6 – Evan Roos (Cell C Sharks)
5 – Emile van Heerden (Cell C Sharks)
4 – JJ van der Mescht (Cell C Sharks)
3 – Asenathi Ntlabakanye (Xerox Golden Lions)
2 – Fezokuhle Mbatha (Cell C Sharks)
1 – Kudzwai Dube (Vodacom Blue Bulls)
16 – Dameon Venter (Xerox Golden Lions)
17 – Nkosikhona Masuku (Xerox Golden Lions)
18 – Hanro Jacobs (Cell C Sharks)
19 – Janko Swanepoel (Vodacom Blue Bulls)
20 – Celimpilo Gumede (Cell C Sharks)
21 – Jaco Labuschagne (Vodacom Blue Bulls)
22 – Dylan Richardson (Cell C Sharks)
23 – Sibusiso Sangweni (Xerox Golden Lions)
24 – Jay Cee Nel (Vodacom Blue Bulls)
25 - Jaden Hendrikse (Cell C Sharks)