Novak Djokovic has been unstoppable in the Adelaide International this summer - and it was here 18 years ago that the Serbian superstar learned to play the 'very aggressive Australian style of tennis'.

Long before all the grand slam titles and the controversy surrounding his vaccination status, Adelaide was once something of a second home to Djokovic.

In early 2004, Adelaide-born Dejan Petrovic - who was once one of Australia's top junior players - had 17-year-old Djokovic join him in Adelaide for a training block.

Petrovic's parents were from Serbia, so the Aussie went out of his way to make the youngster feel as least homesick as possible. 

'I made sure he felt at home,' Petrovic told codesports. 'We made a memorable barbecue at his place in Blair Athol [just north of the Adelaide CBD]. Traditional pig on a spit, all meats on the BBQ, meze. Absolutely everything.

'And, naturally, the Serbian rakija [alcohol]. His parents shouldn't hear this, but we had a couple.'

Petrovic connected the rising teenage star to the local Serbian communities and became a mentor to The Joker. Later that year Djokovic's dad asked Petrovic to take over as his son's full-time coach.

Petrovic retired from his own tennis career right away, knowing that Djokovic was a truly special talent.

'We worked a lot on my transition game to the net and serve,' Djokovic says. 'Very aggressive, in the Australian style of tennis. It was a great time. We had fun times.'

Petrovic explained further:  'The bits about the transition game included moving, through contact then recovering back, that was, for me, essential. 

'He didn't possess this bomb of an inside out forehand that he has today. He had the backhand. He didn't miss, and had more power on the backhand.'

'Plus, the serve is something we worked like crazy to improve.'

Djokovic started to achieve some great results, qualifying for the 2005 Australian Open, The French Open and Wimbledon - where he made it to the third round.

Following the Wimbledon campaign, Djokovic's family decided to go in a different direction with coaching and brought in Italian Riccardo Piatti.

Petrovic, who has been in Adelaide this week watching his old student, says he is proud of the time he spent with the Serbian star and back him to go all the way in the Australian Open.

'I hope he does,' Petrovic says.

'All great things start in Adelaide.'