Ronnie O'Sullivan escaped with a slap on the wrist after snubbing a mandatory post-match press conference following his victory in the first round at the Betfred World Championship.
World Snooker announced O'Sullivan was warned and told he will be fined for any further breaches of discipline.
In a statement, World Snooker said: "Ronnie O'Sullivan has received a formal warning from World Snooker following his failure to fulfil media obligations at the Betfred World Championship on Monday.
"This is in line with World Snooker procedure as it is his first breach of contract this season. Any further breaches will result in a fine and possible referral to the WPBSA (World Professional Billiards and Snooker Association)."
Five-time world champion O'Sullivan beat David Gilbert 10-7 to secure his place in the last 16 at the Crucible.
As well as refusing to attend the press conference, O'Sullivan declined to talk to tournament broadcasters the BBC.
A small fine had been expected, and in the absence of that O'Sullivan will know he is on a last chance.
The 40-year-old was reported in several national newspapers to have been furious about his own performance, with that factor said to have been behind the move to go straight to his dressing room after beating Gilbert and decline to take any questions.
After the match on Monday, World Snooker had said: "All players have a responsibility to the sport, and in particular to their fans. This includes fulfilling media obligations at events. Any players found to be in breach of these rules will be referred to the disciplinary process."
O'Sullivan's behaviour inevitably raises questions over the title favourite's state of mind as he begins preparations for a second-round match against either Barry Hawkins or Zhang Anda, which will begin on Saturday.
However, O'Sullivan causing controversy in Sheffield is nothing new.
Last year he began his campaign in ill-fitting new shoes and had to borrow a pair from tournament director Mike Ganley mid-match, after briefly playing in his socks.
He was warned for making a rude gesture during his second-round match against Matthew Stevens, and was later embroiled in a chalk controversy when he placed the small cube on the table during his quarter-final defeat to eventual champion Stuart Bingham.
He was not fined at any stage.