Nick Kyrgios admitted "emotions got the better of me" after forfeiting his second-round match with Norwegian Casper Ruud at the Italian Open.
The Australian, 24, was in the deciding set when he was given a game penalty, reportedly for swearing, to trail 2-1.
He then kicked a bottle, threw down his racquet, hurled a chair on the court, picked up his bag and walked off.
Kyrgios was fined 20,000 euros (£17,461) for unsportsmanlike conduct and also lost his prize money.
In addition to the prize money of £29,366, he forfeited the 45 ranking points gained during the tournament and was told to cover the costs of his hospitality.
Writing on Instagram, he said: "Very eventful day to say to the least. 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."
Kyrgios has a history of fines for poor behaviour on court and in March clashed with a fan at the Miami Open.
Earlier this week he served underarm during victory over Daniil Medvedev, while his actions on Thursday came as it emerged he told a podcast interview that he "could not stand" Novak Djokovic - who he described as "cringeworthy" - and called Rafael Nadal "super salty".
In the 50-minute interview, Kyrgios, who last year said he was talking to psychologists to address mental health issues, was asked about his opinion on a number of tennis stars.
After branding Roger Federer the "greatest of all time", he went in on Nadal, calling the Spaniard his "polar opposite".
But he had nicer things to say about Britain's Andy Murray, currently out of the game following hip surgery.
"It sucks not seeing him around here, in the locker room he was the best," he said.
Kyrgios' past controversies
Analysis
BBC Tennis correspondent Russell Fuller:
In October 2016, having shown minimal effort in a match with Mischa Zverev in Shanghai, Kyrgios was suspended from ATP tournaments for eight weeks.
A year earlier, in Montreal, Kyrgios had been given a suspended 28-day ban for making a lewd suggestion about Stan Wawrinka's girlfriend.
This time, the Australian can expect at least a heavy fine.
He will be one of the most talked-about people at Roland Garros when the French Open gets under way in 10 days' time. But not because he is thought to have a chance of winning.
Kyrgios is an entertainer, both with a racquet in his hand and when airing his unfiltered views on a podcast, but regularly laments his lack of conditioning.
He is happy to admit he plays too much basketball.
And he knows a coach would probably be a very good idea, but prefers the freedom of only having to answer to himself.