Melbourne Victory suffered a 4-2 loss to Adelaide United in its Foxtel National Youth League opener on Saturday.
Captain Joey Katebian scored a first-half brace for Victory at the Elite Systems Football Centre in Adelaide.
But Dylan Smith netted a hat-trick for the hosts, who set up their win with two goals in the opening 22 minutes.
Katebian struck twice before the break, finishing off a one-on-one eight minutes prior to half-time to make it 2-1.
Antoni Trimboli restored Adelaide's two-goal lead before Katebian struck again, this time with a 25-yard free-kick.
Victory improved in the second half and almost equalised through John Maclean before Smith's late sealer.
Goal machine Katebian praised a young Victory team for its performance, particularly after the interval.
"I think the first half was average. Second half we picked it up a lot," he said.
"Credit to the boys, we had a lot of young boys, a lot of debuts … performance was good, just lacked the finish."
Katebian, 19, said some encouraging words from youth development coach Vaughan Coveny at the break led to Victory's improvement.
"'Cov' spoke about a few things. He just said we need to move the ball quicker, play the ball in behind a bit more and just keep more possession of the ball," he said.
Victory visits the Cleveland Showgrounds to face Brisbane Roar in Conference A next Saturday.
Adelaide United 4 (Smith 15'/22'/89', Trimboli 40')
Melbourne Victory 2 (Katebian 37'/45')