When Dimitri Petratos was let go by Sydney FC a year ago, there was question marks over his attitude and temperament.
The 21-year-old attacker scored his first-ever senior hat-trick as the Roar ensured they would end 2013 at the top of the A-League ladder after a 5-2 demolition of Sydney at Allianz Stadium.
It was the perfect home-coming for Petratos, who was a teen prodigy at the Sky Blues before moving on for greater opportunity 12 months ago.
Mulvey gave the youngster just his third start for the club and he made it count as the Roar bounced back from their shock loss to Newcastle last week with their best performance of the season.
"We didn't play that well last week and I wanted to shake things up a bit," Mulvey said of his decision to make three changes to his starting side.
"(Petratos) was fully deserving of his opportunity because he's got a fantastic attitude.
"He's got great character and I knew that when we released him onto the field.
"He's got so much energy, he's got quality that it doesn’t matter if he's playing against Sydney FC or anyone else."
But there's no doubt Petratos had a point to prove against his former club.
Nothing illustrates that desire more than the fact that Mulvey had assigned Ivan Franjic to penalty duty, only for Petratos to claim the ball – and score – twice from the spot.
Petratos was released by Sydney in December last year after he failed to break into the starting side and also following a heated training ground bust-up with goal-keeper coach Zeljko Kalac.
Sydney coach Frank Farina had yet to join the club when Petratos was let go but couldn't begrudge the young striker of his memorable night.
"I wasn't here when he was at the club so I don't know what issues there were but every player you wish well," the Sky Blues boss said.
"If you have a falling out with a player or they move on, I don't mind if they do well, (but) it's unfortunate (for us) he did it against his old club.
"But it's happened before and it will happen again...good luck to him."
There was nothing lucky though about the ease of the Roar's emphatic win.
Despite going behind against the run of play through Alessandro Del Piero's dipping free-kick, there was only going to be one winner once Thomas Broich equalised on 20 minutes.
Petratos added two more before the break before the visitors went on with the job in the second half, making it nine goals in two games against Sydney this season.
"Some of the football was just beautiful to watch and it was a joy to see the interpassing and the interchanging of positions and the finish at the end of it," Mulvey said.
"Some of our football tonight at times was really good.
"Thomas (Broich) was the orchestrator tonight, he was dropping off and getting into holes and bringing other people into play.
"We have one of the best strikers (Besart Berisha) in the land, he's at home and we scored five and it could've been eight.
"I thought it was a very dominant display."