The match kicks off at 1pm on Friday 14 July at Athlone Sports Stadium, Cape Town and will be streamed on S4C and World Rugby digital channels.
The side has three changes from the starting XV which defeated Georgia last Sunday in Paarl.
The back three of Harri Houston, Tom Fletcher and Llien Morgan remains the same, but Bryn Bradley starts at inside centre, swapping with Joe Westwood who drops to the bench. Bradley will be partnered by Louie Hennessey.
The halfback pairing of Archie Hughes and Dan Edwards remains intact for the fifth consecutive game.
Jones has picked the same front row of Dylan Kelleher-Griffiths, Lewis Lloyd and Kian Hire which started against Georgia but has brought in Evan Hill to replace his injured Ospreys colleague Liam Edwards in the second row. Jonny Green will pack down alongside him.
Lucas De La Rua, who scored as a replacement against the Georgians, starts on the openside flank, replacing Seb Driscoll with captain Ryan Woodman and Morgan Morse starting at blindside and No 8 respectively.
Cardiff Met prop Tom Pritchard is in line to earn his first appearance at the championship after being name on the bench.
Jones was delighted with the victory against the nuggety Georgians but expects the Junior Wallabies to provide an entirely different proposition.
“A lot of things came together on what we had been working on – it felt like we had put on a more polished performance together around our whole game,” he said.
“Our set piece finished strong against Georgia. Our team management was really good particularly in comparison to the second half against New Zealand. The boys learned the lessons, but we know for this match we are going to have to go up another couple of gears again.
“We’re expecting a much more expansive game, not that Georgia aren’t an expansive team but the conditions in Paarl were quite difficult under foot and the ball was a little bit greasy so we couldn’t move the ball into space.
“The pitch is going to be wider, drier and the weather prospects a little bit better overhead. I think Australia will look to move the ball to the edges a lot more efficiently than Georgia so they provide a different challenge. But I’m confident if we get the defence right like we did against Georgia, we can deal with it.”
Wales U20 v Australia U20, Friday 14 July, Athlone Stadium, KO 1pm (UK), S4C live
15 Harri Houston (Ospreys)
14 Tom Florence (Ospreys)
13 Louie Hennessey (Bath Rugby)
12 Bryn Bradley (Harlequins)
11 Llien Morgan (Ospreys)
10 Dan Edwards (Ospreys)
9 Archie Hughes (Scarlets);
1 Dylan Kelleher-Griffiths (Dragons RFC)
2 Lewis Lloyd (Ospreys)
3 Kian Hire (Ospreys)
4 Evan Hill (Ospreys)
5 Jonny Green (Harlequins)
6 Ryan Woodman (Dragons RFC – Capt)
7 Lucas De La Rua (Cardiff Rugby)
8 Morgan Morse (Ospreys)|
16 Lewis Morgan (Scarlets)
17 Louis Fletcher (Ospreys)
18 Tom Pritchard (Cardiff Met)
19 Mackenzie Martin (Cardiff Rugby)
20 Gwilym Evans (Cardiff Rugby)
21 Joe Westwood (Dragons RFC)
22 Harri Wilde (Cardiff Rugby)
23 Harri Williams (Ampthill)