Novak Djokovic has stirred anger after calling for peace in northern Kosovo after winning his first match at the French Open.
Here's a breakdown of what he said and what it has to do with the unrest in the sovereign European state.
What did Novak Djokovic say?
After winning his match, Djokovic signed the camera for a Serbian television network.
This isn't unusual — winning players regularly sign television cameras after winning their matches.
However, instead of just signing his name on the screen, Djokovic wrote "Kosovo is the heart of Serbia. Stop the violence," in Serbian.
Djokovic explained his decision to write the message to Serbian media in a press conference after the game.
"Kosovo is our hearth, stronghold, centre of the most important events for our country," he said in Serbian.
"The biggest battle happened there, the most important monasteries are there.
"There are many reasons why I wrote it on the camera."
Djokovic later reposted an image of his signed message on his Instagram account.
Why are people angry about this?
Because the Republic of Kosovo declared independence from Serbia back in 2008 after the Kosovo Albanian uprising against repressive Serbian rule.
Kosovo says more than 100 countries recognise it as a sovereign state, including Australia.
But Serbia, its northern neighbour, still considers Kosovo part of its territory and Serbia's traditional ally Russia doesn't recognise the country's independence.
Kosovo, which is also bordered by Albania, North Macedonia and Montenegro, has been grappling with unrest for decades.
North Atlantic Treaty Organization (NATO) forces have been running peacekeeping operations in the region since 1999.
Petrit Selimi, Kosovo's former foreign minister, said claiming Kosovo was the heart of Serbia was an "unacceptable political, irredentist message".
"So if a Russian player tomorrow writes 'Crimea and Donbas are heart of Russia. Stop violence' it’s all cool? Djokovic has a history of support for Serbian nationalist causes," he wrote on Twitter.
What's happening in Kosovo now?
There's been protests about recent elections in Kosovo's north, where the majority of the population is Serbian.
Many Serbs boycotted the election and tensions flared when Albanian mayors took office.
Serbian protesters demanded the Kosovo government remove Albanian mayors and reinstate Serbian-financed leaders.
Peacekeepers, known as Kosovo Force (KFOR), have been helping local police protect four municipal buildings from Serb protesters since Friday.
Twenty-five NATO peacekeepers have been injured so far.
KFOR said soldiers sustained "trauma wounds with fractures and burns" after they were attacked with incendiary devices by protesters in the town of Zvecan.
This prompted the federal government to tell Australians to avoid travelling to Kosovo's northern region after reviewing its advice on the Smart Traveller website on Tuesday.
"We've reviewed our advice for Kosovo," the site now says.
"We haven't changed the level of our advice, exercise a high degree of caution overall.
"Higher levels apply in some areas.
"Reconsider your need to travel to Leposavić, Zubin Potok and Zvečan municipalities and North Mitrovica."
Are tennis players allowed to make commentary?
"There are no official Grand Slam rules on what players can or cannot say," the French tennis federation (FFT), who organises the event, told Reuters.
"The FFT will not be making any statement or taking any stance on this matter."
However, the International Tennis Federation (ITF), the world governing body for tennis, suspended Russia and Belarus teams's membership in March last year.
It suspended Russia because of the nation's invasion of Ukraine.
The ITF included Belarus - one of Russia's closest allies - in this for allowing Russian troops to launch attacks from Belarusian soil.
Russian and Belarusian players are still able to compete in tournaments, but they're only allowed to do so as individuals - not under their flag our country's name.
Daniil Medvedev, Russia's highest-ranking player, is listed on the ITF website with no mention of his country or flag:
Normally, players's country and flag is displayed on their ITF profile.
Back in January, the Australian Open banned spectators from bringing Russian and Belarusian flags to matches.
The ban came after attendees waved the Russian flag during a match between Ukraine's Kateryna Baindl and Russia's Kamilla Rakhimova.
Shortly after the ban, Djokovic's father Srdjan Djokovic, was criticised for posing in a video with tennis fans waving a Russian flag outside the tournament.
One of the men in the video was wearing a shirt symbol "Z" which, in this context, is a symbol signalling support for Russia's invasion of Ukraine.
"I had no intention of being caught up in this," the tennis star's father said in a statement.
"My family has lived through the horror of war, and we wish only for peace."
ABC with wires
