The world champion rattled in three century breaks to overcome the Welshman, including a 142 clearance in frame seven.

O'Sullivan will now play Ireland's Ken Doherty in Sunday's final after the Irishman defeated England's Stephen Lee 9-7 in his semi.

Williams, UK champion in 1999, did not go down without a fight and looked like he would prove more than a match for his opponent when knocking in a break of 86 in the opening frame.

But the 'Essex Exocet' immediately went one better with an 87 to level and, after the next two frames were shared, he took three in succession to lead 5-2.

Williams won the last frame of the afternoon and the first of the evening, with a break of 67, to trail by one.

But that was as close as the left-hander got.

Sullivan went 7-4 up and was never in danger from the on, adding a break of 131 in frame 13.

"That was the best form of my life," said O'Sullivan, who claimed the UK crown in 1993 and 1997.

"It was an unbelievable match to play in - there are electric waves going through me.

"Mark played out of his skin. I scored heavily and didn't miss a long pot all day, but I couldn't shake him off.

"I'm not looking forward to playing him for the next five or six years.

"I hope he gets married, goes off to live in Spain and spend his life lying on a beach!

"He's a class act. Sometimes I just sit there and learn from him."

Williams responded: "Ronnie played well - give him half a chance and he clears the table.

"I put him under pressure, but he's got the ability to kick on when he needs to."

Frame scores: (O'Sullivan first): 8-122 87-0 58-59 107-22 (107 break) 55-37 70-1 142-0 (142 break) 2-68 16-75 74-48 71-48 0-93 131-0 (131 break) 0-72 65-19.