The Johnny Warren Medal winner has revealed how he had to kick the habit of constant nightclubbing as a young player and undergo a dramatic transformation on his way to becoming the player he is today.
The Serbian import has been crucial in Sydney FC's record-breaking season as the Premier's Plate winners vie to also claim the championship trophy in Sunday's grand final against fierce rivals Melbourne Victory.
Insiders at Sydney praise Ninkovic's work ethic and say his attention to detail with his preparation is meticulous.
But that's a far cry from the attitude he had at the begging of his career.
When Ninkovic signed to Ukrainian side Dynamo Kyiv as a 19-year-old in 2004 he fell into the trap of having too good a time at the expense of his football.
"When I came to Ukraine I was 19 years old and it was a beautiful country," Ninkovic told The World Game
"I spent a lot of my time in nightclubs and I was getting a lot of injuries. First two years I didn't play many games because I was injured all the time.
"Everyone when they're 19 years old goes to nightclubs and everything, and I would go out to these clubs a lot, but then the next day I have to go to training.
"It was very hard and that's why I was injured many times."
Ninkovic said it was the advice from wiser heads that eventually convinced him he had to make sacrifices if he wanted to become as good a footballer as he could be.
"A friend of mine who played for Dynamo Kyiv, he was older than me and he was from Serbia as well and he talked to me a lot," Ninkovic said.
"He said I needed to do this, to do that, and if I wanted to play football I had to change something.
"I spoke with the president from Dynamo Kyiv and all the time he said you need to change yourself if you want to be a top footballer, if you want to go every night to the nightclubs you can't play professional football.
"What they said helped a lot and after a couple of years I started to change myself."
But more than just a physical change, Ninkovic also transformed himself spiritually.
He said the process became complete after he met his future wife, Dejana, and embraced the Serbian Orthodox religion.
"I met Dejana and I started to go to church every Sunday," he said.
"I started the fasting and started to believe in God and started to change myself and after that I started to play many games. I wasn't getting injuries."
Ninkovic, now 32, went on to have nine successful seasons with Dynamo Kyiv, winning two Ukrainian Premier League titles, three Cup trophies and four Super Cups, before joining Serbian side Red Star Belgrade and winning the title with them.
He joined the Sky Blues last season from French club Evian and has been a standout in the A-League ever since.
The midfield maestro was on Monday announced as a runaway winner of the Johnny Warren Medal beating Perth's Spanish import Diego Castro, who claimed the honour last season.
On Sunday Ninkovic will be looking for even more silverware to add to his already well-stocked cabinet.