An inexperienced Australia were beaten 1-0 by South Korea despite dominating large periods of their friendly international in Busan.
Australia were unbeaten in five of their past six games against South Korea heading into the contest and arguably deserved to extend that sequence in front of 55,000 partisan fans.
The Socceroos started the stronger with striker Mitchell Duke, playing his first international since 2013, going close to opening the scoring in the 10th minute.
Awer Mabil then volleyed across the face of goal before debutant Brandon O'Neill's corner found Duke, whose goal-bound header deflected off the right hand post.
Midfielder O'Neill and fellow Sydney FC A-League premiership winner Andrew Redmayne both made encouraging debuts for the Socceroos, while Brandon Borello and Ryan Williams also earned their first caps as substitutes.
Goalkeeper Redmayne made two strong saves inside the opening 20 minutes and Bailey Wright also had an impressive outing in coach Graham Arnold's back four.
South Korea gained momentum in the second half and, after having a penalty appeal waved away in the 52nd minute, the hosts persevered to put Redmayne under more pressure.
Redmayne did prevent Tottenham star Son Heung-Min from doubling the lead with stellar save eight minutes from time.
Adam Taggart, playing his first international for five years, came off the bench in search of an equaliser but could not find the target to leave the Socceroos with just six goals from six games since their group-stage exit at the 2018 World Cup in Russia.