O'Sullivan added the latest chapter to the story of a career loaded with controversy when he conceded his quarter-final against the Scot after only five frames, when he was trailing 4-1.
The 31-year-old from Essex had just won his first frame and was on a break of 24 when he attempted to cut in a red, but missed, and immediately went to shake hands with Hendry and referee Jan Verhaas.
Apart from briefly stopping off at Hendry's dressing-room to wish his opponent well, O'Sullivan immediately left the Barbican Centre without offering any explanation for his actions.
Even by O'Sullivan's standards it was a dramatic turn of events and officials of World Snooker must now decide whether to punish the player for the embarrassment he has heaped on their second most prestigious ranking tournament.
But in a statement released by his PR representatives, the world No3 later apologised for letting down his large contingent of supporters and admitted he had done the wrong thing.
"I wish I could have played a better game today but I had a bad day in the office," said O'Sullivan. "Anyone who knows me knows I'm a perfectionist when it comes to my game and today I got so annoyed with myself that I lost my patience and walked away from a game that, with hindsight, I should have continued.
"I wish I could have given Steven a better game and I'm sorry I didn't stick around to sharpen him up for his semi-final. I'm also really sorry to let down the fans who came to see me play - it wasn't my intention to disappoint them and for that I am truly apologetic.
"At this moment I am feeling disappointed with myself and I am hurt and numb, but I am a fighter and I will be back on my feet fighting stronger and harder than ever very soon."
Hendry insisted he had taken no satisfaction from O'Sullivan's exit, which meant the Scot was awarded a 9-1 victory that sent him through to a semi-final against Graeme Dott or Steve Davis.
The world No1 refused to condemn O'Sullivan, with whom he has clashed in the past, and maintained he would have preferred to continue a match that had promised to be the best of this event so far. "It's just bizarre," said Hendry. "But I'm not going to criticise Ronnie because I don't know his reasons, his thoughts or if anything is wrong. He came into my dressing- room and said 'good luck for the rest of the tournament'. I asked if there was anything wrong and he said 'No, I'm just fed up, I've had enough'."
KNOWING YOU ARE BEATEN
In February this year, golfer Daly withdrew from the FBR Open after nine holes of the second round. Four over for the day, he knew he was missing the cut - and on his last hole 'putted' with a sand wedge. "I'm done," said Daly, who then marched to the car park and drove off, later citing illness. His abrupt departure would have been a surprise, if it hadn't been the ninth time he'd quit.
In a 1980 title fight, Sugar Ray Leonard was well on top in the eighth round when Duran was alleged to have said to the referee "no mas, no mas" - no more, no more. The contest was over.