The hyperbole bellowing out from Srdjan Djokovic’s loudhailer in recent days was no surprise to those familiar with the world No 1 tennis player’s father.

Behind Novak – the man at the centre of an unprecedented political storm in sport – are parents just as steadfast in their opinions, and even more outspoken.

“I call on all Australians and the whole world to raise their voice against terror, and the brutal human rights violations of the world’s best tennis player,” Srdjan has screamed during recent rallies in their native Belgrade.

Yet for years before he was branding Australia’s Prime Minister a “dictator” and calling on the Queen to step in, Srdjan had regularly turned his ire on Djokovic rival Roger Federer.

Their dispute stems back to the mid 2000s, after the protective father took exception to Federer criticising Djokovic during a 2006 Davis Cup tie for regularly calling for medical treatment over a sinus problem. A feud then deepened when the Swiss directed a “keep quiet” comment in Srdjan’s direction during a match at the Monte Carlo Masters in 2008.

While the two players have always remained relatively gracious towards one another since, Srdjan has been unable to hold his tongue, and launched his most blistering attack on Federer in an interview with Newsweek Europe. Recalling events 10 years’ earlier, he said: “Novak was just 19 at the time. He had a deviation of his sinuses and couldn’t breathe. And Federer tried in every possible way to disrespect him because of his breathing problem.”

derer, he added, had “shown himself to be the best player in the world but not as a good person at that time”. His son has expressed awkwardness over the comment, but Srdjan appeared to double down on his position in an interview last year, telling Serbian television that Federer was “not such a good man”. “About 15 years ago Federer attacked my son when he was still young, he was 18 or 19 years old,” he told the station, K1. “I knew someone would be there who would be better than him. So I said that [Federer] was a great champion, the best at the time. But as much as he is a great champion, Federer is not such a good m

Srdjan has since demanded that Federer retires. “Go man, raise children, do something else, go ski, do something,” he said. Tennis, Srdjan added, was “not my whole life, it is just my son’s current hobby”.

In reality, however, he and his wife have been as dedicated as tennis families come to ensuring Novak’s progress in the sport since he got started in the unlikely location of a ski resort, aged just seven.

Srdjan, a former professional skier and instructor, had opened a creperie, pizza parlour and sports clothes business in the Serbian mountains when Novak was two. Mother Dijana, who has been equally critical of Australia while flanking her husband at rallies in Belgrade in recent days, was in charge day-to-day at the restaurant and would send Novak across the road to three tennis courts, where his natural talents would be discovered by renowned coach Jelena Gencic.

She told the family they had a “golden child”, and within months Novak was travelling with his ever-enterprising father to America, Germany, and Italy for the best training possible in tennis academies. By the time Djokovic was 10, the family had left their mountain resort entirely.

The context of Novak’s childhood, growing up during the break-up of Yugoslavia, and having family roots not far away in troubled Mitrovica, goes some way to explaining why his parents have never ducked controversy.

It is not only Australian authorities and Federer who felt the sharpness of Srdjan’s outbursts since his son made it to the top of tennis. Of Rafa Nadal, he reportedly says: “(Nadal) was his best friend while he was winning. When things changed, they were no longer friends… This is not a sport.”

And while they have been supported by political leaders in Serbia in recent days, the family have previously endured strained relations with authorities. While Djokovic has largely kept his counsel, there have been rows with the Serbian Tennis Federation over previous demands for government support in their tennis projects.

‘Dijana is one of the most important Serbians’

With his against-the-odds journey to the top in mind, both his mother and father have stated that the world No 1 is the best in history. While such a description is doubted elsewhere, many in Serbia agree. In a Belgrade museum, hangs a mosaic made by Jovan Kentera, a Montenegrin artist, who manufactured a mosaic of his mother, depicting Dijana as the Virgin Mary.

“Dijana is the mother of the new era, and one of the most important Serbians,” the artist has said. “She has created and raised such a man, who is the pride of all of us, but also of people in the world. Dijana is a saint.”

With such praise ringing in their ears, perhaps the family can be forgiven for cranking up the rhetoric in recent days.