Ronnie O'Sullivan, who is defending the Maplin UK Championship, and Mark Williams, a former champion, have both reached the last 16 of the tournament while Stephen Hendry made his exit on the first weekend at Telford.

O'Sullivan's opening salvo in his attempt to win the title for the fifth time was to take a 6-0 lead over Rory McLeod by an overwhelming points tally of 541-19 that included two centuries, 117 and 110. McLeod, who coaches the Qatar national team, sprang suddenly to life with a hat-trick of centuries and would have levelled at 6-6 but for O'Sullivan clearing with 38 to win the 12th frame on the pink. The world champion went three up with four to play by winning the next from 47-0 down with a run of 94 and clinched victory two frames later. "Every credit to Rory," said O'Sullivan. "At 6-0 his head could have gone down but he stuck in and gave it a real go."

Williams, the UK champion in 1999 and 2002, led Mark Selby 7-3 but potted only one ball in the next four frames as the Masters champion rolled in breaks of 82, 139, 103 and 100. An outstanding green was key to the Welsh left-hander shading the 15th frame before he shut Selby out in the next to prevail 9-7.

"It's an excellent win for me," said Williams, who is emerging from a long sojourn in the doldrums. "Apart from O'Sullivan, who's in a different class out on his own, Selby's the next player in my opinion. I've practised 11-12 hours a day to stop myself playing like an arse."

All seemed well for Hendry, going for his sixth UK title, when he led Stephen Lee 5-2 but his 9-7 defeat extended a drought in titles which dates back to February 2005. "The one good thing was how badly I played and still lost only 9-7," he said. "There's nothing wrong with my game. It's my head I have to sort out.

"It's hard to pot balls when there's chaos inside my head. I know what causes it but I'm not going to tell you. People talk about how good the standard is but, if I got 30% of my old form back, I'd be competing."

Lee, who has himself suffered a dip in form over recent seasons, told BBC2: "I'm feeling quite good under pressure and it's just a matter of enjoying it again."

The 34-year-old pondered quitting snooker after his first-round exit from the World Championship in April but says he has rediscovered his appetite for the game. "Enjoyment is what it's all about. I would have probably found something else to do with myself," he said.

Judd Trump, the 19-year-old Bristol left-hander who beat O'Sullivan in reaching October's Grand Prix semi-finals, went down 9-8 on the final pink to the vastly experienced Mark King who he felt should have been warned for swearing. "He was swearing every time he missed a ball. He even swore when someone shouted: 'Come on Judd,'" he said.