Melbourne Victory was edged 1-0 by North Geelong Warriors in its opening game of the NPL2 West season on Sunday.
Victory enjoyed the majority of possession as the Warriors sat back at Epping Stadium, but it was unable to break through.
A second-half goal from Darius Madison following a corner proved to be the difference between the sides.
Victory head coach Gareth Naven rued his team's lapse from the set-piece, but said it was getting better at dealing with it.
"Leading into this game, we've talked about our preparation and understanding this type of competition and where it affects us," he said.
"There's no secret – we get affected massively on set-pieces. We're working extremely hard to prevent that happening and if it does happen, to deal with it. As you can see today, in every shape and form, we didn't deal with it. In saying that, they are getting better at it.
"If I look through the number of set-pieces delivered today, we are winning contests more, keeping people outside the box, keeping people outside the six-yard box, we're actually achieving some good things.
"Previously, we've been a little bit unaware of how to do that. I think the boys are definitely getting better at understanding that.
"I'm very happy with how competitive they were and understand that teams aren't going to bully us and I think that's quite evident out there which is good for the players. We're a year older than last year so I think they understand what they're in for.
"We had a lot of possession and possibly at times the end product wasn't the best and maybe being a little bit smarter in our strategy to understand getting the ball to where there's less players where then we can damage teams, not keeping the ball in their strengths where we get hurt from it, especially in transition. All things we're well aware of as a group, but continually getting better in our preparation.
"I was happy with their attitude, application today, but it all comes down to the small moments that kill us a bit and that small moment killed us a bit."
Victory made a bright start, with Brandon Lauton and Nicholas Hatzigeorgiou combining well in the middle and Nicholas Sette causing huge problems down the right.
But the visitor had two great chances, Victory goalkeeper Matthew Sutton making a good save at his near post to deny Madison before Domenico Marafioti struck the crossbar from range for the Warriors.
Victory forward Pierce Waring volleyed over from inside the area after a clipped pass from Cameron McGilp late in the half, while Sutton again denied Madison.
The Warriors took the lead early in the second half as Madison poked in after a corner.
It was all Victory for the remainder of the half, Waring blazing over from inside the area in the 57th minute in its best chance.
Earlier, Victory's under-20s started their title defence with a 1-0 loss to North Geelong.
Victory is at home again in Round 2, hosting Brunswick City at Epping Stadium on Sunday, February 25.
NPL2 West 2018 Round 1
Melbourne Victory 0
North Geelong Warriors 1 (Darius Madison 51')
Melbourne Victory: Matthew Sutton; Andrew Visciglio, Benjamin Carrigan, Cameron McGilp, Jonathan Vakirtzis (Jack Palazzolo); Nicholas Hatzigeorgiou, Brandon Lauton; Nicholas Sette, Birkan Kirdar, Joshua Kelic (Maker Maker); Pierce Waring (Nuh Sehavdic).