By BBC Sport's Clive Everton

Centuries provide some indication of scoring power and Ronnie O'Sullivan made three in important frames in his semi-final win over Mark Williams.

O'Sullivan's 107 brought him level at 2-2, his 142 opened up a three-frame gap of 5-2 and his 131 put him three-up with four to play.

That gave him the 9-6 win which put him through to Sunday's UK Championship Final at York against Ken Doherty.

In contrast Doherty won his semi-final against Stephen Lee on Friday mostly in bits and pieces, fluking the pink to win 9-7.

Doherty is a fine tactician but will need to score more heavily on Sunday to prevent O'Sullivan adding the UK Championship to his world title.

Only Steve Davis, Stephen Hendry, John Parrott, John Higgins and Williams have held those titles at the same time.

Of all the players who have ever played the game O'Sullivan and - albeit less so than a few years ago - Hendry are the two most likely to win a frame in a single scoring visit.

It does not necessarily have to be a century because 90, 80 and usually 70 achieve this just as effectively.

In nine years as a professional O'Sullivan's tally of centuries stands at 266.

That is only 14 fewer than Davis, who is slowing to a trickle in this category, has made in 23 years.

Hendry has made 544 but O'Sullivan is only 25-years-old while Hendry is 33 next month.

Doherty is himself one of only 15 players to have made 100 centuries in competition but his preferred style is a judicious mixture of attack and defence.

In his previous UK final seven years ago Doherty trailed Hendry only 6-5, Hendry having made six centuries, then lost 10-5 with Hendry making seven.

Shrewd

Doherty is one of the circuit's most astute tacticians, a very shrewd calculator of risk and difficulty against potential gain. Of course, this is of only limited value if created openings are not exploited.

I expect Doherty, the world number four, to do better than he did against Lee, the world number eight, because in his own mind he will have less to lose.

The worst thing that can happen to him is that he will walk away with �54,000 with his marriage on December 28 to Dr Sarah Prasad, an Australian psychiatrist practising in Dublin, to look forward to.

Winning is not out of the question but the odds must favour O'Sullivan securing his third UK title and the �100,000 first prize.

Beating Peter Ebdon from four-down with five to play in Thursday's quarter-final seemed to have given him new impetus and yesterday his clarification of remarks he made afterwards was welcome.

O'Sullivan said of Ebdon then: "He plays like an amateur, he's got no class."

He claimed on Saturday to have expressed himself carelessly in the heat of the moment.

Courage

"I was a bit disappointed that Peter said I'd had some luck. That got under my skin a bit.

"Luck had nothing to do with it. Peter played out of his skin in the afternoon then I came alight when I was 8-4 down.

"It needed a bit of faith, a bit of courage."

And prodigious talent as well.