Tommy Reffell will start the Under-20s World Championships in the Wales back row to face host nation Argentina on Tuesday.
Leicester Tigers flanker Reffell, who captained Wales in this event last season, wears the No7 shirt for the match in Rosario.
Club colleague Sam Costelow, part of this season's Under-18 League winners with Tigers, is also in the Wales squad but is not included for this opening fixture.
The pool also includes defending champions France and Fiji as well as the hosts who finished in sixth place last season, one spot ahead of Wales.
Reffell, who missed out on most of the Six Nations with injury, is pleased to be back in action and said: "Obviously it was disappointing to miss out on it, but I’ve been in a training camp last year and I’ve been training hard with my club, so it’s not like I’ve been away from rugby for a long time.
"It was frustrating [to watch the Six Nations], because as a young player you just want to play and it’s never nice to be on the sidelines."
Tackling the host nation in the opening fixture presents a big challenge and Reffell added: "I think they were really emotional when we played them [before]. They’re a good team and it’s definitely a challenge.
"Overall, I think we’ve got a very exciting squad this year and it’s a good mix of players who have been to an Under-20s World Cup before and a good group of young lads who are really wanting to make a name for themselves."
Kick-off on Tuesday is at 5.00pm UK time and there is live coverage on S4C.
Wales Under-20s: 15 Ioan Davies (Cardiff Blues), 14 Rio Dyer (Dragons), 13 Aneurin Owen (Dragons), 12 Tiaan Thomas-Wheeler (Ospreys), 11 Ryan Conbeer (Scarlets), 10 Cai Evans (Ospreys), 9 Harri Morgan (Ospreys); 1 Kemsley Mathias (Scarlets), 2 Dewi Lake (Ospreys)(c), 3 Ben Warren (Cardiff Blues), 4 Morgan Jones (Scarlets), 5 Jac Price (Scarlets), 6 Lennon Greggains (Dragons), 7 Tommy Reffell (Leicester Tigers), 8 Jac Morgan (Aberavon/Scarlets)
Replacements: Will Griffiths (Dragons), Garin Lloyd (Ospreys), Rhys Davies (Ospreys), Tom Devine (Dragons), Nick English (Bristol Bears), Teddy Williams (Cardiff Blues), Ed Scragg (Dragons), Iestyn Rees (Scarlets), Dafydd Buckland (Dragons), Max Llewellyn (Cardiff Blues), Deon Smith (Dragons), Tomi Lewis (Scarlets).