Boris Becker has warned Novak Djokovic he risks the wrath of the Australian Open crowd if his quest for a record 21st grand slam title continues in Melbourne next week.

Djokovic’s participation is still in limbo as he awaits a verdict from Australian immigration minister Alex Hawke, who is considering whether to cancel his visa despite the Serbian’s court victory on Monday.

While Serbian fans celebrated outside the court-house on Monday, many Australians, who have endured months of hard lockdowns, remain angry at the current decision to allow the unvaccinated Djokovic to enter the country.

Becker, who coached Djokovic for three seasons from 2014 to 2016, told the BBC: “I’m sure there will be a couple of boos and whistles, but he’s used to that.

“He was always a street-fighter who had to fight the odds and win over the crowd, and it was fascinating in last year’s US Open final when they finally embraced him.

“The crowd will be difficult with him but with each match he starts, he will win the crowd and they will embrace him again. But he is going to have a difficult first week.”

Whilst expressing his full support for Djokovic’s stance, Becker admitted he was concerned at the prospect of similar problems in the future, and reiterated his belief that the world number one should accept a vaccine.

“I’m sure the French Open and Wimbledon will be watching the Melbourne saga, and I’m sure they will have strict rules on who can play and who cannot play,” Becker added.

“It’s everybody’s choice but life is more difficult if you don’t want to be vaccinated. Personally I’d advise him to be vaccinated eventually because life would be easier for him, but ultimately it’s his choice and we have to respect that.”

A number of fellow players have expressed concerns over Djokovic’s potential exemption, although Rafael Nadal offered belated support for the decision on Monday, having previously intimated it was wrong for his great rival to seek to enter Australia.

Wimbledon quarter-finalist Marton Fucsovics provided a glimpse of the mood in the locker room by saying he does not think the Serbian had the right to play in the tournament.

Speaking to the Hungarian outlet M4Sport, Fucsovics said: “People’s health is paramount, and there are rules that were outlined months ago, namely that everyone should vaccinate themselves – and Djokovic didn’t.

“From this point of view, I don’t think he would have the right to be here.”

The Hungarian world number 38, who lost to Djokovic in last year’s Wimbledon quarter-finals and in the Paris Masters in November, also said he was not alone in thinking it unfair that Djokovic could play in the gram slam event despite not being vaccinated.

The 29-year-old said news of the world number one’s exemption had received a negative reception among many tennis players.

Djokovic has returned to training in Melbourne while Minister Hawke considers whether to invoke extraordinary powers to send the Serbian home.

The star still has questions to answer, such as why he was pictured at a series of public engagements in the days following his second positive coronavirus test on December 16.

An attempt to broach the subject during a news conference staged by the Djokovic family in Belgrade on Monday was ignored.

Meanwhile, Australian prime minister Scott Morrison has spoken with his Serbian counterpart about Djokovic’s situation and explained Australia’s “non-discriminatory border policy”.

“The PM had a constructive call with PM Brnabic this morning on Novak Djokovic,” a statement from the Australian Prime Minister’s Office read.

“The PM explained our non-discriminatory border policy and its role in protecting Australia during the Covid-19 pandemic.

“They both agreed to stay in contact on the issue, and to further strengthening the bilateral relationship.”

Former Australia cricketer Shane Warne branded his country’s handling of the affair as a “shambles” but insisted it was their right to refuse entry.

Warne told the BBC: “It just seems an absolute, embarrassing mess.

“Novak is well entitled not to be jabbed or to be jabbed, but it is also Australia’s choice to not let him in or to let him in.

“I don’t know what’s actually going on here. It’s a shambles and bit embarrassing.”