Paul Okon's side battled bravely despite losing a man with a third of the game left to play, but ultimately fell 2-1 to their hosts in Lisbon
The Young Socceroos began their two-game series against Portugal's Under-20 side with a cruel 2-1 defeat in Lisbon on Thursday.
Having played the final 30 minutes with 10 men, Australia's resistance was finally broken Aladje netted the match winner deep into injury time.
Australia controlled possession for large periods of the first half but they were eventually made to pay for their inability to take full advantage of their dominance.
The hosts hit the front through a Joao Mario penalty just on the hour-mark after the referee adjudged Adam Taggart to have handled the ball in the area.
Portugal's goal capped off a horrible few minutes for Paul Okon's side following the dismissal of defender Connor Chapman, having been deemed the last man in the challenge that led to the free kick in which Taggart handled.
But Taggart went from zero to hero as Australia leveled the match five minutes later, after latching on to a through ball from Newcastle United youngster Curtis Good.
With the match seeming likely to finish as a stalemate, Portugal broke the tourist's hearts after Aladje got on the end of a delightful cross from substitute To-Ze with virtually the last kick of the game.
Despite the loss, Young Socceroos manager Okon could not fault his players.
"Today's game was against a world class opponent. We had a game plan which the players executed to perfection which was really pleasing," said Okon.
"Against teams like Portugal you have to take your opportunities and we created two very good chances in the first half and should have been leading 2-0 at half-time.
"Connor Chapman’s red card left us with 10 men for nearly 30 minutes, but we continued to play good attacking football and Adam Taggart's great goal was a reward for the whole effort of the team.
"While it was disappointing to concede a goal in the final minute of extra-time it does not take away from an outstanding performance from the whole team."
The two nations will meet again on Sunday at the National Stadium in Lisbon.