In Mitch Langerak's first game for the club since 2010, Nikos Vergos headed home in the 24th minute to give Victory the lead at AAMI Park.
Bruno Fornaroli scored in the 90th minute to deliver Victory's first win in 47 days, snapping a six-game winless run.
Victory hadn't won since beating Perth Glory on December 8, which ultimately proved Kisnorbo's last game before his departure for Yokohama F. Marinos.
"It's a nice feeling, definitely a nice feeling," Diles said.
"And nice to be rewarded for their hard work, because it's been a month now of hard work and some good performances, and in the end, you keep going and you get rewarded.
"Tonight, maybe performance-wise wasn't great, probably not one of our better games. But in the end, we got the result.
"This job is never easy for anybody. Doesn't matter whether you're winning or losing.
"And in the end, the most important thing tonight is that the players have been rewarded for the last six games, and that's all I care about.Â
"Yes, it gets a monkey off your back, but in the end, they've been rewarded for their work and their performances, and that's the most important thing for me."
Diles, yet to be officially handed the full-time gig, has Victory fifth, a point clear of seventh-placed Sydney.
Langerak, who replaced Jack Duncan, made his first ALM appearance in 5424 days, since the 2009-10 grand final loss to Sydney.
Daniel Arzani and Fornaroli dropped to the bench for Nishan Velupillay and Vergos.
Socceroos coach Tony Popovic, who this week said Arzani had been "poor" in October's national team camp and needed to "raise his level", was among those watching on.
This header is as good as it gets 😮�💨🔥 FIRST BLOOD TO — Isuzu UTE A-League (@aleaguemen) @gomvfc IN THE BIG BLUE!Nikos Vergos returns to Victory starting XI with a bang at AAMI Park 💥Watch #MVCvSYD live and exclusive NOW on Paramount+ 📺 pic.twitter.com/3fw606xWw8January 24, 2025
Victory took the lead when Ryan Teague's outswinging corner was well-met by Vergos, who rose to power the ball home.
Soon after, Sydney were awarded a penalty when Roderick Miranda clipped Anas Ouahim, but the call was changed to a free kick after VAR showed contact happened outside the box.
Klimala whipped a shot wide in the 37th while Joe Lolley blasted over the bar in the 70th.
Fornaroli sealed three points when he pounced on a Kasey Bos long ball, shrugged off a defender and rounded Devenish-Meares to finish from a tight angle.
"I think we had a total of eight shots today and one on target," Sydney boss Ufuk Talay said.
"Makes it difficult to score goals if we're not hitting the target and making the keeper work."
Victory play Perth away next Saturday, when Sydney host Adelaide.
