The Socceroos have lamented earning a lesson in physicality from Ecuador in a 2-1 loss that put a dampener on their post-World Cup return to Australia.
Four days after Australia beat Ecuador 3-1 in Sydney, they drew first blood via Brandon Borrello's first international goal.
Though Borrello appeared offside, the goal gave Australia an early lift, but they failed to go with a physical Ecuador in front of 27,103 fans at Marvel Stadium, conceding two second-half goals via a penalty and from a corner.
"Overall if there's one big lesson we learned tonight for the young boys was the physicality of the game and the speed," coach Graham Arnold told reporters.
"One of the best things was how strong they were and how well they held the ball up when they needed to, and we couldn't manhandle them.
"The boys will go away with a great lesson that they have to work harder in the gym, they've got to work harder on the pitch, they've got to work hard playing those type of games and the experience of playing those games is the most important thing."
Defender Milos Degenek echoed Arnold's thoughts.
"At different stages throughout the game we should have asserted ourselves a bit more in that physicality," he told reporters.
"We should have been a bit stronger - especially when we play at home. They've come to us and we need to show them that this is our home ground."
Adelaide United goalkeeper Joe Gauci starred on debut with three excellent first-half saves, denying Kevin Rodriguez in the fourth and 22nd minutes and Felix Torres in the 23rd.
But Gauci, 22, could do nothing to stop Pervis Estupinan's penalty, after Thomas Deng brought down Kevin Rodriguez, in the 53rd minute, or William Pacho's excellent header 12 minutes later.
"He was fantastic, he was brilliant," Arnold said of Gauci.
"The goals, they weren't any fault of his - and sloppy goals, the penalty and from a corner."
Riley McGree was contentiously denied a penalty after Piero Hincapie clattered into the midfielder in the 45th minute.
"I thought it was a penalty," McGree told reporters.
"But I'm the player who got fouled so I'm always going to say it was a penalty."
Arnold made seven changes to his starting line-up from Sydney.
Melburnian Jackson Irvine captained the Socceroos for the first time, Gauci replaced Mat Ryan (minor groin injury), and Bailey Wright replaced Harry Souttar (ankle).
But Wright and Thomas Deng, who replaced Kye Rowles but was hooked for him in the second half, were given nightmares by Rodriguez.
"They might have at times had a bit too much respect for him," Degenek said.
There were nasty scenes in the 27th minute when Cameron Devlin was left streaming blood from an accidental knee to the head from Pacho, but he returned to play.
Melbourne City youngster Jordan Bos debuted in the second half, but Arnold opted not to turn to Adelaide teen sensation Nestory Irankunda.
"Of course (it was tempting to bring Irankunda on) but you've got to remember the kid's just starting the journey," Arnold said.