Ben Davies has warned that Ryan Giggs' youngsters must grow up fast on the international stage or Wales' Euro 2020 qualification ambitions will perish.
Wales meet Hungary in Budapest on Tuesday in a game which has taken on added importance after the weekend's Group E results.
Hungary moved to the top of the section by winning 3-1 in Azerbaijan, three points ahead of Wales - who have a game in hand - after the Dragons were beaten 2-1 by Croatia.
The youthful nature of the side was reflected by the fact that six of the starting XI have made their international bows since Giggs was appointed Wales manager 17 months ago.
"This is their first real taste of international football," Tottenham defender Davies said of the young players in Giggs' squad.
"But we haven't got too much time for that learning curve if we want to qualify for the Euros.
"Sometimes it doesn't matter how you win games.
"It's just making sure that we stop the opposition from doing their thing and show a better account of ourselves."
Wales were forced to play catch-up on a scorching afternoon in Osijek.
Croatia led 2-0 through a James Lawrence own goal and an Ivan Perisic strike at the start of the second half as the home side dominated courtesy of Luka Modric's midfield mastery.
But Wales fought back through substitute David Brooks' deflected drive and had late chances to snatch a draw as Giggs' side finished strongly.