An injury time goal to Daniel Barac has broken AIS hearts and given the Western Sydney Wanderers a come-from-behind 2-1 win in the National Youth League at Campbelltown Stadium on Sunday.
The AIS looked on course for their first points of the campaign when Joshua Barresi's blistering volley gave them a well-deserved 1-0 lead at the break.
But the Wanderers refused to go away and equalised through Kwabena Appiah-Kubi with just 12 minutes left before Paric prodded home the winner at the death.
Barac, who was a second half substitute, was on hand to finish off after good lead-up work from Zakeriya Elrich.
It was a cruel blow for Tony Vidmar's young AIS side who were more than competitive for long periods of the match and will feel they should have come away with at least a draw.
But it was a vital three points for the Wanderers who have kept themselves in touch with the leading sides after grounding out their second win of the season.
Despite coming off and 8-0 hiding against Sydney FC midweek, it was the visitors that started full of confidence, pinning the Wanderers back deep in their own half.
While Wanderers striker Mark Cindric went close to opening the scoring midway through the half with a stinging shot that went narrowly wide, it was no surprise when the AIS went in front on 26 minutes through Barresi.
The attacking midfielder was quickest to a clever ball in behind the Wanderers defence before hitting a sweet right-foot volley that flew past keeper Thomas Manos and in off the far post.
Barresi was involved in the AIS' next chance 10 minutes later, his pinpoint pass put skipper Scott Galloway through on goal but his first touch was too heavy and Manos was able to save.
The home side's best chances were coming from corners and they went close to equalising on two occasions before the break.
First defender Stepjan Paric's near-post flick on was cleared off the line by Liam Rose on 40 minutes before Wanderers captain Yianni Perkatis blazed over from close range in stoppage time.
Disappointed at his side's first half showing, Wanderers coach Trevor Morgan made a triple change at the break and they immediately looked more threatening.
One of those substitutes Nicholas Olsen should have done better with his chance seven minutes after the resumption but he fired his volley high and wide.
While the home side were on the front foot, the AIS youngsters were still dangerous on the break and could have doubled their lead on the hour when Todd Norris' 25-metre shot smashed onto the crossbar.
It proved a vital let-off for the Wanderers, who regrouped and drew level 12 minutes from time through Appiah-Kubi.
Sent through via a sublime pass from Jacob Williams, the pacy attacker steadied himself before finishing clinically past a stranded Andre Jannese from a tight angle eight metres out.
It set up a grandstand finish with Barac having the final say with his late, late winner.
Western Sydney Wanderers 2 (Appiah-Kubi 78, Barac 90+1)
AIS 1 (Barresi 26)
Western Sydney Wanderers: 20. Thomas Manos (gk), 2. Brian Jamba (13. Jacob Williams – 46), Stepjan Paric, 4. James Baldacchino, 5. Jayden Koulizakis, 6. Alastair Quinn, 7. Zakeriya Elrich, 8. Yianni Perkatis (c), 9. Mark Cindric (12. Nicholas Olsen – 46), 10. Jack Madgwick (11. Daniel Barac – 46), 14. Kwabena Appiah-Kubi
AIS: 20. Andre Jannese (gk), 2. Darcy Madden, 3. Brendan Gonano (13. Jeremy Tshongo – 59), 4. Ben Warland, 5. Matthew Schmidt (14. Jack Iredale – 33), 8. Joshua Barresi, 9. Todd Norris, 15. Scott Galloway, 18. Alexander Gersbach, 19. Bright Appiah (22. Liam Rose – 69), 22. Liam Rose (6. Matthew Ntoumenopulos – 59)