Paris - Hailed as one of the greatest tennis players of all time, Novak Djokovic was aiming to defend his title at this year's Australian Open and win a record 21st Grand Slam.
But his refusal to get vaccinated against Covid-19 pitted him against the Australian government, who cancelled his visa and left the tennis ace facing deportation on the eve of the tournament.
AFP Sport looks at other controversial incidents that have dogged the career of the world number one and 20-time Grand Slam title winner.
US Open default
Djokovic saw his 2020 US Open title hopes dashed when he was sensationally disqualified from his last-16 match against Pablo Carreno Busta after accidentally hitting a female line judge in the throat with a ball.
The Serbian had lashed out in frustration after dropping serve in a match played on an empty Arthur Ashe Court where fans were banned due to the pandemic.
"This whole situation has left me really sad and empty," Djokovic said in a statement.
"I checked on the linesperson and the tournament told me that thank God she is feeling OK. I'm extremely sorry to have caused her such stress. So unintended. So wrong."
In the midst of the pandemic in 2020, and with professional tennis shut down, Djokovic organised the Adria Tour, a series of exhibition events in the Balkans.
However, the tournament was abandoned in Zadar in Croatia after Bulgarian player Grigor Dimitrov tested positive for coronavirus.
Djokovic and his wife Jelena as well as fellow players Viktor Troicki and Borna Coric also went on to reveal positive tests.
The players were also heavily criticised for dancing and embracing at a nightclub.
When Djokovic arrived in Melbourne for the 2021 Australian Open, he whipped up another storm for issuing a list of requests that reportedly included players being given private homes with tennis courts.
"Djokovic is a tool," firebrand Aussie player Nick Kyrgios tweeted in response.
Ironically, Kyrgios has leapt to Djokovic's defence during his current Australian controversy.
"I just think it's crazy. I feel so sorry for him," he said Saturday.
Djokovic has long faced accusations that he exaggerates injuries in matches.
At the 2008 US Open, he took two medical timeouts in a gruelling five-set win over Tommy Robredo.
Quarter-final opponent Andy Roddick then mockingly listed Djokovic's injuries to include "two hurt ankles, bird flu and SARS!"
Djokovic defeated the American and hit back in his post-match, on-court interview.
"Well, obviously Andy was saying I had 16 injuries last match... and obviously I don't," he said.
At the 2020 French Open, vanquished quarter-final rival Carreno Busta was dismayed to see the trainer called to tend to the Serb.
"Every time a match gets complicated he asks for medical assistance," said the Spaniard.
At the 2021 Australian Open, American player Taylor Fritz was equally scathing after Djokovic needed five sets to win their third-round clash.
Djokovic said he was suffering an abdominal strain.
"If he was really, really injured, he wouldn't have kept playing," said Fritz.
Djokovic went on to claim a ninth Australian Open title.
Water way to go
Djokovic came under fire when he claimed it was possible to alter the composition of water and food through positive thinking.
In an online exchange with 'wellness guru' Chervin Jafarieh, the world number one said: "I've seen people and I know some people that through energetical transformation, through the power of prayer, through the power of gratitude, they manage to turn the most toxic food or the most polluted water, into the most healing water.
"Because water reacts and scientists have proven that molecules in the water react to our emotions to what is being said."
Former player and respected TV pundit Mary Carillo told The Tennis Channel that she hoped Djokovic would back down on his claims.
"I'm very disturbed that Djokovic and that other guy are saying you can change toxic water to drinking water," she said. "This is dangerous stuff."