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.”

Federer, 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 man.”

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.