Matthew Stevens cashed in on a below-par performance from red-hot favourite Mark Williams to take a massive step last night towards winning his first Embassy World Championship final. Stevens won six of the eight frames in the second session of the best-of-35 final to move into a 10-6 overnight advantage.

Now the 22-year-old needs only to win eight of the remaining 19 frames to topple his Welsh compatriot and gain revenge for his 10-8 reversal in the UK Championship earlier this season.

Stevens also had the distinction of notching the 50th century of this year's championship in the 12th frame.

Williams, 1 to 2 with the bookmakers at the start of the match, showed in his semi-final against John Higgins that he is capable of coming back from such a deficit when he recovered from 15-11 down to win 17-15.

But he looked visibly tired after those heroics and there was little of that sparkle on show this evening.

Williams was second best in the tactical battle and was guilty of trying too much to force the pace. Too often he appeared to lack patience and Stevens was able to take advantage to telling effect.

The pattern was set from the start and Stevens also profited from a double kiss on the penultimate red and a fluked double on the final one to move 5-4 ahead.

Williams led 37-6 in the next but Stevens needed no second invitation when he got amongst the balls with a 78 clearance.

The 11th frame was strewn with errors from both players before Stevens edged home but he was in impressive form in the last before the interval.

His 111 brought up the 50th century of this year's championships and was the fifth frame he had won on the trot after trailing 4-3 in the afternoon session.

It was indication of Williams' problems that his highest break in the four frames was only 29.

Stevens made it back-to-back centuries with a run of 114 in the first frame after the resumption to make it six frames in a row before Williams finally broke his duck for the evening with the help of a 59.

Stevens restored his five-frame advantage with a 73 break in the 15th frame before Williams gained some crumbs of comfort with a 69 in the last of the evening.

Meanwhile, Northern Ireland's Joe Swail has created a small slice of snooker history via his thrilling run to the semi-finals. Swail has become the first player to drop out of the leading 32 in the rankings and then regain his place in the top 16.

He spent one season amongst snooker's elite in 1994-'95 when he reached number 12 in the world. The 30-year-old will now occupy the number 16 position for the 2000-2001 season after defeating Paul Hunter, John Parrott and Dominic Dale on the way to the last four.

It has been a thrilling rollercoaster ride for Swail who in the final qualifying round came from 9-6 in arrears to defeat Stephen Maguire 10-9 at Preston to book his place at the Crucible Theatre.

And his achievements in the 2000 tournament were yesterday recognised by the sponsors who presented Swail with an Embassy special merit award.

Swail received a clock and a £500 cheque from Graham Blashill, managing director of Imperial Tobacco, before the start of the final. Blashill said: "His sportsmanship and good humour have been a credit to the game."

Swail - who is 40 per cent deaf in both ears - had his run finally ended by Stevens when the Welshman won 17-12 but he pocketed Stg£70,000 in prize money which was the biggest payday of his career.