The Socceroos slipped to a 2-1 loss to Ecuador in Melbourne to put a dampener on their first series in Australia since the World Cup.
Four days after Australia beat Ecuador 3-1, they drew first blood via Brandon Borrello's first international goal.
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Though Borrello appeared offside, the goal gave Australia an early lift, but they failed to compete with a physical Ecuador in front of 27,103 fans at Marvel Stadium.
Riley McGree was also contentiously denied a penalty after Piero Hincapie clattered into the midfielder in the 45th minute.
Adelaide United goalkeeper Joe Gauci starred on debut with three excellent first-half saves.
But Gauci could do nothing to stop Pervis Estupinan's penalty in the 53rd minute, before William Pacho scored an excellent header from a corner in the 65th minute to complete Ecuador's turnaround.
Graham Arnold made seven changes to his starting line-up from Sydney.
Jackson Irvine captained the Socceroos for the first time, Gauci replaced 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 all night by Kevin Rodriguez.
Gauci was called into action in the fourth minute when Rodriguez burst away from Wright and cracked a shot on target, with the 22-year-old getting down low for a brilliant one-handed save.
The Socceroos took the lead when Irvine teed up Craig Goodwin, who slipped as he smacked a long-range shot into the post.
The ball deflected out fortuitously to Borrello, who sizzled a first-time left-footed strike home.
In the 22nd minute, Rodriguez outmuscled Deng and got a shot away, but again met his match in Gauci, who turned the ball to safety.
Gauci made another sharp stop to deny a Felix Torres header from the subsequent corner.
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.
Ecuador fired a warning shot when Junior Somoza blasted over the bar in the 31st minute.
McGree was incensed when he didn't receive a penalty late in the half.
Six minutes into the second half, Fernandez cut inside Deng and the defender brought him down from behind, with Ecuador skipper Estupinan coolly burying the subsequent penalty.
For Ecuador's second, Pacho cleverly disguised his run and peeled off Australia's defenders to head home a lovely corner from Junior Sornoza.
Melbourne City youngster Jordan Bos made his international debut in the second half, but Arnold opted not to turn to Adelaide teen sensation Nestory Irankunda.