James Whittingham has had to withdraw from the Wales Under-20 squad for the 2015 World Rugby U20 Championship.
The concussed centre's place is taken by Cardiff Blues team-mate and wing Elis Wyn Benham in the 28-man squad.
The tournament in Italy runs from 2-20 June and Wales will face France on 2 June, then play defending champions England and Japan in their pool.
Benham missed the junior Six Nations through injury but has now got his place back in the Wales squad.
"It's an amazing feeling, I've had a late call-up," Benham said.
"Unfortunately I hurt my hamstring earlier in the Six Nations, but now I've been given a new chance I'm really looking forward to it."
Newport Gwent Dragons Tyler Morgan has been removed from the squad to join the senior squad following injury to Clermont Auvergne centre Jonathan Davies.
He has been replaced in the Under-20s party by Dragons' team-mate Barney Nightingale.
Wales Under 20 team manager Mark Taylor said: "This is a fantastic opportunity for Tyler, we wish him all the very best over the summer.
"It also gives Barney Nightingale the opportunity to further develop his rugby at the World Rugby U20 Championship."
Wales Under-20 squad:
Forwards: Luke Garrett (Dragons/ Cross Keys), Keagan Bale (Dragons/ Cross Keys), Dillon Lewis (Blues/ Pontypridd), Joe Jones (Blues/ Cardiff), Leon Brown (Dragons/ Cross Keys), Ryan Elias (Scarlets/ Carmarthen), Liam Belcher (Blues/ Pontypridd), Torin Myhill (Scarlets/ Llanelli), Rory Thornton (Ospreys/ Bridgend), Adam Beard (Ospreys/ Aberavon), Seb Davies (Blues/ Pontypridd), Lee Taylor (Carmarthen), Tom Phillips (Scarlets/ Llanelli), Ollie Griffiths (Dragons/ Newport), Harrison Keddie (Dragons/ Ebbw Vale), Jon Fox (Ospreys/ Swansea).
Backs: Tomos Williams (Blues/ Pontypridd), Kieran Hardy (Scarlets/ Carmarthen), Jarrod Evans (Blues/ Pontypridd), Daniel Jones (Scarlets/ Carmarthen), Garyn Smith (Blues/ Pontypridd), Lloyd Lewis (Dragons/ Newport) Barney Nightingale (Dragons/ Newport), Owen Watkin (Ospreys/ Bridgend), Joshua Adams (Scarlets/ Llanelli), Joe Thomas (Ospreys/ Swansea), Elis Wyn Benham (Blues/ Cardiff), Dafydd Howells (Ospreys/ Neath).