A snooker referee once had to persuade Ronnie O'Sullivan to finish a 147 break. At the 2010 World Open in Glasgow, the Rocket was facing Mark King.

Early in the frame, when he was on eight points, Sullivan paused to ask referee Jan Verhaas what the reward was for a maximum clearance. In extraordinary scenes, Verhaas was unaware, so he requested nearby officials to discover the answer, with O'Sullivan taking a minute and a half before playing his next shot.

Upon discovering there was no 147 bonus prize - only £4,000 for the tournament's highest break - he informed the official he wouldn't complete it. In what turned out to be the match-winning frame, the break proceeded until he potted the pink and moved to shake King's hand, only for Verhaas to encourage him to pot the black.

O'Sullivan confessed after the match: "I wasn't going to pot the black because to make 147 and not really get a nice bonus was a bit disappointing because they are magical moments and they deserve magical bonuses.

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"But the ref played a guilt trip on me and said, 'Come on, do it for your fans.' And I thought, 'OK, because I haven't got long to play anyway, so I might as well go out on a high.' But I wasn't going to pot it because four grand, once you've paid the taxes..."

Verhaas, now a refereeing assessor with WST after retiring from front-line officiating, told the Framed podcast last year: "Throughout the break, he kept chatting to me, saying, 'I'm not going to do it.'

"I could sense he was going to leave that black or the pink. I thought, 'I've got to say something.' Before the match, I was chatting to fans who'd come from Spain to watch Ronnie.

O'Sullivan asks Verhaas if there is a 147 bonus(Image: WST)

"I said to him, 'Do it for your fans.' He said I played with his conscience. It was one of those strange moments but I'm glad I did it."

There's been further high-break drama at the ongoing World Open in Yushan, China, where the Rocket astonishingly made a 153 break in his quarter-final triumph over Ryan Day.

With a free ball after Day had fouled, a 155 was actually feasible at one point. However, 153 is still the highest break ever in professional snooker, surpassing Jamie Burnett's 148 in 2004.

O'Sullivan with Ryan Day after his 153 break(Image: TNT Sports)

Despite the highest break prize at the World Open being a mere £5,000, there was no hint this time that the seven-time world champion would halt his progress.

The record-breaking frame was the first of the match, which O'Sullivan won 5-0 to set up a semi-final clash against Wu Yize.