World Snooker Championship 2012: Mark Allen accuses Cao Yupeng of dishonesty
Mark Allen accused Cao Yupeng of dishonesty during his surprise first-round defeat by the Chinese player at the World Championship in Sheffield.
Allen, who admits he was "completely outplayed" by the world number 81, claimed Cao failed to declare an illegal push shot when leading 5-4.
No foul was given and the 26-year-old Northern Irishman eventually lost 10-6.
"I'm disgusted. The state of snooker is very sad if it has to be down to that, but it's not the first time," he said.
"Cao looked at the referee, too, so I'm very confident on where I stand on that."
Referee Paul Collier took no action at the time, with television replays proving inconclusive.
Former Crucible champion Terry Griffiths, who coaches Allen, said during live commentary: "I think he fouled that. I think he hit the white twice."
Players are expected to declare fouls when officials fail to spot such infringements.
After the match, Allen said: "I thought the big turning point was at 5-4 when he was in the balls and... the referee missed a blatant push.
"It was quite obvious to me and anyone who was watching at home would have been able to see it.
"It was a big stage of the match. If the referee rightfully called a foul there, I'd have had a chance of going to 5-5 and the match would have been different, but he went on to pull away."
Asked in the post-match media conference whether he recalled the incident, Cao answered through an interpreter: "No.
"I was just focusing on playing. I didn't realise if I had fouled. If I fouled, I say sorry. If I didn't foul, and Mark said that, then I would feel very upset and angry."
A World Snooker spokesman confirmed Allen's comments would be examined by the World Professional Billiards and Snooker Association.
BBC Sport pundit and six-time world champion Steve Davis said: "He obviously questioned his opponent's integrity.
"In football you see players falling over fresh air, you see people handling the ball and not owning up to it.
"The dilemma is: whose responsibility is it, the referee's responsibility or the player's responsibility?
"The actual incident is arguable [but] Mark felt strongly enough to say what he did."
It is not the first time that Allen has caused controversy on the circuit.
"Dead cat found this morning," he tweeted. "Any wonder this place stinks. Must be dead cats all round the town."
In December, he called on World Snooker chairman Barry Hearn to resign after changes were made to the format of major tournaments.
"I've got no doubt he'll tweak the World Championship," Allen said at the time. "The whole tradition of the game is going to pot."
Allen was fined for the Hearn outburst, while his Haikou World Open comments are still being assessed by the snooker authorities.