O'Sullivan, who made a 147 at the age of 15 in the English Amateur Championship, another in the 1997 Embassy World Championship in only 5min 20sec and two more this year, in the Regal Welsh Open in January and last month's Grand Prix at Preston, failed at a long red on 104 after taking blacks with his first 13 reds. Having won a Vauxhall Vectra for his Preston effort, he could have earned another. "I'm after a dealership," he said.
Brown, the world No 83 from St Helens, who beat Thailand's top player, James Wattana, in the previous round and five opponents including Jimmy White, to reach the final phase of next month's China International in Shanghai, reduced his 3-0 arrears to 3-2 but O'Sullivan raced through the remaining three frames of the morning in only 23 minutes, the last with a break of 108.
The three evening frames extended O'Sullivan's winning streak to six but such are the standards by which this prodigy judges himself that his satisfaction was muted. "I've had something wrong with my game for seven years. I'm still searching for what it is and I've got my discipline back. I should have won a lot more than I have and that's demoralising," he said.
Suffering from nervous exhaustion and depression, he was unable to defend his UK title last year and has not won a tournament of any description for 14 months.
Stephen Hendry, seven times world champion and attempting to win his sixth UK title, survived precariously from three down with four to play to beat Jason Ferguson, the world No 50, 9-8 on Thursday and was again in difficulty before running out a 9-6 winner over Stuart Pettman, the world No 68 from Preston to set up a last-16 encounter with the local favourite, Paul Wykes, tomorrow.
Pettman, 4-1 down, led 6-5 and was in play with 50, heading for 75, when a routine pink to a middle pocket eluded him. Hendry summoned a timely 41 clearance to snatch that frame on the black, made 67 to pink from 51 behind to lead 6-7 - two clearances he acknowledged "made a big difference" - and restricted Pettman to a mere five points in the remaining two frames.
Again, though, Hendry was disappointingly short of the form he has been producing in practice: "I don't know what it is. I can't seem to focus on the tournament. It is very frustrating," he said.
John Higgins, the defending champion, trailed his fellow Scot, Chris Small 3-1, but won the four remaining frames of the day, the last on the black, to lead 5-3 overnight. Mark Williams will resume this afternoon with a commanding 7-1 lead over Michael Judge.Reuse content