Sam Costelow made his Championship debut for Wales in their World Under-20s fixture against defending champions France on Saturday.
With Leicester Tigers colleague Tommy Reffell again coming through the full 80 minutes, fly-half Costelow was introduced as a replacement midway through the second half.
Wales, who won their opening game against tournament hosts Argentina, celebrated two tries from Scarlets wing Tomi Lewis but the French earned an impressive 32-13 victory.
Costelow, who was an Under-18 League winner with Tigers for a second time this season, earned promotion from the national squad at that level to the Under-20s ahead of the Championships.
Wales face Fiji in the final round of pool fixtures on Wednesday.
England also have one win from two games as they bounced back from defeat by Ireland in the opening round to beat Italy in Santa Fe.
With Tigers prop Joe Heyes playing from the bench after starting against the Irish, England had to claw their way ahead with a late try and then a penalty to win 24-23.
England claimed tries through forwards Alex Coles, Tom Willis and Richard Capstick but missed out on a bonus point despite the late winning kick from Josh Hodge.
Australia, who have a maximum 10 points from two rounds, are next up for England on Wednesday.
Head coach Steve Bates said: "It was a tough game, Italy played well but we put them under a lot of pressure but didn’t turn that pressure into points and they capitalised on the opportunities they had.
"We will look back and say we made far too many individual mistakes, but credit to our guys for fighting back to get the victory and they should be proud of that.”