Novak Djokovic became just the ninth player in tennis' Open era to be disqualified from a match after the world No 1 inadvertently hit a line judge with a ball during his US Open fourth round match against Pablo Carreno Busta.
Fines, warnings, and code violations are common occurrences in professional tennis but disqualifications are much rarer, hence the huge reaction to Djokovic's default on Sunday.
Here is a look at the nine occasions when tennis players were disqualified from matches.
John McEnroe (1990 Australian Open)
Perhaps no surprise that the first player to be disqualified in the Open era was none other than the John McEnroe, one of tennis' most infamous bad boys. Competing in the fourth round of the 1990 Australian Open against Sweden’s Mikael Pernfors, American McEnroe was disqualified after collecting three code violations.
The first, for unsportsmanlike conduct, came in the third set when McEnroe stopped in front of a lineswoman, whom he believed had made a bad call, and glared at her while bouncing a ball on his racquet.
The second was for racket abuse in the fourth set when McEnroe twice threw his racquet to the ground, with the second throw causing a crack in the racquet's head. That violation swiftly led to the third when McEnroe unleashed a volley of verbal abuse at umpire Gerry Armstrong, who with the support of Ken Farrar, the Grand Slam chief of supervisors, issued the final violation and with it disqualification.
Tim Henman (1995 Wimbledon)
Before he became the darling of British tennis, Tim Henman was the cause of an unsavoury incident that led to him and his doubles partner Jeremy Bates being disqualified at Wimbledon in 1995.
After putting a volley in the net, Henman reacted angrily by hitting a ball with full force, accidentally hitting a ball girl in the ear. Cue tears from the ball girl and loud gasps from the crowd before the umpire decided to default the match and send opponents Henrik Holm and Jeff Tarango into the second round.
Henman apologised to the ball girl soon after and presented her with a bouquet of flowers.
Irina Spirlea (1996 Palermo Open)
Irina Spirlea became the first female player to be disqualified from a WTA match after she was verbally abusive towards a match official in Palermo, Italy.
The Romanian, who reached a career high world No 7, was also involved in another high-profile moment of controversy when she appeared to intentionally bump into Venus Williams when both players were walking back to their chairs during a changeover in the 1997 US Open semi-finals.
Anastasia Rodionova (2007 Cincinnati Open)
Anastasia Rodionova became the second woman to default a match after she hit a ball at spectators who were cheering on opponent Angelique Kerber during their 2007 Cincinnati Open match.
Tournament referee William Coffey swiftly defaulted the Russian, who attempted to protest what she believed was a harsh punishment.
"I've never seen in my life anyone defaulted in this situation," she said. "I'm shocked. I still don't understand why they defaulted me. I'm really upset.
"I had no warning. I didn't hit the ball at anybody. I didn't swear at anybody. I didn't throw my racquet."
Stefan Koubek (2007 Metz Open)
Leading Sebastien Grosjean 4-2 in the final set of their match in Metz, Stefan Koubek was disqualified for using abusive language towards tournament supervisor Thomas Karlberg while disputing a call.
Austrian Koubek maintained he was directing his language toward the situation and not the official but that was not enough to save him from defaulting the match.
Koubek, a former world No 20, was seething in his comments after the incident.
"Of course, I'm still very angry about the whole thing a day after. But nothing can be changed: we players are at the mercy of the supervisors for better or for worse."
David Nalbandian (2012 Queen's Club)
Seemingly on course for the 12th title of his career, David Nalbandian was disqualified from the 2012 Queen's final after kicking an advertising board and injuring a line judge.
The incident happened with the Argentine leading Marin Cilic 7-6, 3-4. A strong kick smashed the advertising panel in front of line judge Andrew McDougall's seat, causing heavy bleeding to his leg.
Chair umpire Fergus Murphy awarded the match, and the title, to Cilic before Nalbandian issued a strange explanation for his actions.
"It's a tough moment to end a final like that but sometimes we feel so much pressure from the ATP playing so many tournaments," he said. "There are a lot of rules and sometimes they don't do anything. The rule book is very big and I can tell you the ATP do a lot to the players and nothing happens."
Denis Shapovalov (2017 Davis Cup)
Denis Shapovalov is now regarded as one of the finest young talents on the ATP Tour, but three years ago the Canadian grabbed the headlines for a far less positive reason.
Competing for Canada against Great Britain in the Davis Cup, a then 17-year-old Shapovalov hammered a ball out of court in frustration while trailing Kyle Edmund 6-3 6-4 2-1. That ball found the eye of French umpire Arnaud Gabas and the match was defaulted.
"Luckily he was OK but obviously it's unacceptable behaviour from me," said Shapovalov. "I just feel awful for letting my team down, for letting my country down, for acting in a way that I would never want to act.
"I can promise that's the last time I will do anything like that. I'm going to learn from this and try to move past it."
Nick Kyrgios (2019 Italian Open)
Nick Kyrgios is no stranger to on-court controversy but this incident at the 2019 Italian Open is the only time the Australian was disqualified from a match.
Playing Norway's Casper Ruud in the second round and with the score at 1-1 in the deciding set, Kyrgios was given a game penalty for apparently swearing at a line judge. The penalty cause Kyrgios to erupt as he slammed his racquet to the court, kicked over a water bottle and threw a chair onto the court.
The umpire called the match referee to the court but before Kyrgios could be officially disqualified, the Australian packed up his bags and stormed out of the arena.
“Very eventful day to say the least," Kyrgios later wrote on Instagram. "Emotions got the better of me and I just wanted to say that the atmosphere was crazy out there today, just super unfortunate that it had to end in a default. Sorry Roma, see you again, maybe.”
Novak Djokovic (2020 US Open)
Taking to the court on Sunday evening against Pablo Carreno Busta, Novak Djokovic was widely expected to seal a routine win and continue what felt to be an inevitable march toward an 18th Grand Slam title.
Then, having dropped serve to trail 5-6 in the opening set, the world No 1 hit a ball toward the back of the court, hitting a line judge in the throat. She quickly fell to the ground as Djokovic swiftly went over to assist her.
After a lengthy conversation between tournament officials, Djokovic was disqualified, sending Carreno Busta in the last-eight in New York.
"I'm extremely sorry to have caused her such stress. So unintended. So wrong."