Melbourne Victory was edged 2-1 by Whittlesea Ranges in the NPL2 West on Sunday.
After going ahead through Nicholas Sette at Epping Stadium, Victory was pegged back by an Anthony Ramzy goal in the first half.
Despite having its chances, Victory went down after Jose Luis Ramires Soto scored a late winner for Whittlesea.
Victory took an early lead through Sette, who scored his fifth goal of the season.
Jack Palazzolo, 18, was played in behind before squaring for the winger to open the scoring.
While Brady Quinn went close midway through the first half, Whittlesea started to control proceedings.
Ranges levelled 10 minutes before half-time, Ramzy finding the bottom corner with a neat finish.
Victory had a great chance to restore its lead approaching the hour-mark, but Whittlesea goalkeeper Gian Tapia denied Palazzolo after a lovely Jack Morton pass.
Liston Diaz, who like Morton came off the bench, poked a Palazzolo cross wide with 20 minutes remaining.
Diaz, 17, had two more late chances, but Whittlesea found a late winner as Soto's strike from distance proved too hard to handle for Mawith.
Head coach Gareth Naven
"We started off well and scored a goal, a little bit erratic in possession in the first half, played a little bit of basketball, couldn't get a sense of our rhythm because if you keep passing the ball inside of pressure, it gives the opposition the chance to grab hold of you, to win the ball back and we were very slow in trying to move it out of pressure. That improved a little bit in the second half.
"I thought also the effort was inconsistent from first half to second half. There were moments in the game where at times there were some good passages, but at the same time we need to be more consistent in that approach.
"The competition we're in is an important competition and as a team we've got to understand that. Disappointed in the end to concede a late goal. In saying that, we created two or three chances that we could've made something better of it but we didn't finish the chances off. Overall, me and the staff are a little bit disappointed in our approach today."
Victory's under-20s continued their title push, extending their unbeaten run to five matches with a 2-1 win over the Whittlesea Ranges.
NPL2 West 2018 Round 26
Melbourne Victory 1 (Nicholas Sette 11')
Whittlesea Ranges 2 (Anthony Ramzy 35', Jose Luis Ramires Soto 85')
Melbourne Victory: Majak Mawith; Brandon Lauton, Benjamin Carrigan (c), Matthew Bozinovski, So Nishikawa (Jack Morton); Thierry Iradukunda, Nicholas Hatzigeorgiou; Nicholas Sette (Liston Diaz), Brady Quinn, Yazid Said; Jack Palazzolo.
Victory faces Sunshine George Cross at Knights Stadium on Saturday, September 1.