Prop Ollie McKenna returns to the front row alongside captain Joe Roberts, with Dan Halkon partnering Alfie Blackett in the second row. Alex Bryden starts at inside centre while Jackson Rennie is on the bench.
Glasgow Hawks' Harvey Preston shifts to number eight after scoring in Scotland's 44-26 victory over Argentina. Ayr's Jamie McAughtrie covers hooker on the bench.
McKenna is one of four changes made by head coach Fergus Pringle as Scotland look to equal their best-ever finish at the tournament. Roberts will again captain the side after scoring twice in the win over Argentina.
Scotland take on Wales at the Avchala Stadium on Friday, with kick-off at 5.30pm BST.
Scotland U20
15 Rory McHaffie (Edinburgh Rugby)
14 Daniel Kelly (Edinburgh Rugby)
13 Henry Kesterton (Edinburgh Rugby)
12 Alex Bryden (Glasgow Warriors)
11 Nairn Moncrieff (Edinburgh Rugby)
10 Jake Dalziel (Merchiston Castle/Newcastle Red Bulls) Vice-Captain
9 Asa Stewart-Harris (Saracens RFC)
1 Ollie McKenna (Glasgow Warriors)
2 Joe Roberts (Glasgow Warriors) Captain
3 Ollie Blyth-Lafferty (Edinburgh Rugby)
4 Alfie Blackett (Cardiff Metropolitan University)
5 Dan Halkon (Glasgow Warriors)
6 Christian Lindsay (Edinburgh Rugby)
7 Jack Utterson (Edinburgh Rugby)
8 Harvey Preston (Glasgow Hawks)
Substitutes
16 Jamie McAughtrie (Ayr RFC)
17 Jamie Stewart (Edinburgh Rugby)
18 Jackson Rennie (Glasgow Warriors)
19 Finlay Mather (Grammar Tec)
20 Oliver Finlayson Russell (University of St Andrews)
21 Matthew Fick (Edinburgh Rugby)
22 Calum Jessop (Heriots RFC)
23 Ewan Caven (Gloucester Rugby/Nottingham University)