SNOOKER/World Championship: Ronnie O'Sullivan rocketed towards the Embassy World Championship final yesterday when, with sublime brilliance for four frames and ruthless efficiency for the rest of the afternoon, he took a 13-3 lead over seven-time champion Stephen Hendry. The Londoner now needs only four more frames today for victory and raises the possibility that only one of today's scheduled two sessions will be required.

O'Sullivan's first two visits to the table brought breaks of 81 and 92, and in the fourth he added a 117, his 12th century of this championship in pursuit of Hendry's record of 16 in 2002.

The third frame proved an exception when the 2001 champion ran out of position on 19, but returned with a clinching 52.

Not having missed a single pot at that stage while a frame was still alive, O'Sullivan had restricted Hendry to just 15 points in proceeding from his overnight 6-2 to 10-2.

O'Sullivan did not score as heavily after the intermission, but he maintained his cocoon of concentration. Not even the prospect of a £147,000 (€218,000) jackpot for a maximum diverted his attention in the sixth frame. After six red-blacks, he preferred to retain position for a certain pink when he could have lost it for black.

To the relief of Joe Perry, who had set the target at 145 for the highest-break prize worth £17,600 (€26,000), O'Sullivan broke down on 63.

Runs of 52 and 42 followed, helped by errors from Hendry, whose focus had clearly been hit by O'Sullivan's relentless pressure, although the seven-time champion did at least avoid the indignity of a session whitewash through the late 44 which gave him the concluding frame.

In the other semi-final, Graeme Dott, resumed at 5-3 up against Matthew Stevens but lost one frame of dreadful errors and another to a break of 84. However, he settled to his first century of the championship, 117, to regain the lead 6-5. A late 50 from 24 behind opened a two-frame gap, and by keeping Stevens scoreless in the next he led 8-5.

But he may rue missing the last black of a 34-minute frame from its spot which would have taken him to 9-5 instead of 8-6.

Dott began the third session impressively with a break of 61 to the final yellow which extended his advantage to 10-7.

The Scot looked full of confidence, but errors began to creep into his play and 2000 finalist Stevens took full advantage.

Dott broke off in frame 18 and left Stevens a red into the black pocket which he sank to set him on the way to a fine 104 - his second century of the best of 33 match.

In the next, Dott made a mess of an attempted safety shot with reds scattered all over the table and Stevens again took full toll with a run of 84.

Stevens looked to be growing in belief and he went into the interval all square with the help of 52 in frame 20.

Then, after the break, he found himself ahead for the first time at 11-10 with a break of 73, but Dott showed that he was not about to buckle. A 74 in the next made it all square again and 42 and 47 in the next enabled the 26-year-old to edge back in front.

Stevens was first amongst the balls in the final frame of the session but Dott responded with a superb 69 to the final black for a 13-11 lead.

Now Dott will need to win only four of the remaining nine frames to cross the finishing line and set up a likely meeting with red-hot favourite O'Sullivan.

It remains to be seen how much Dott's exertions have taken out of him should he reach the final and retain his place in the top 16. He has already fought out 86 frames - far more than any other tournament he has participated in - whereas O'Sullivan has breezed comfortably through the last two rounds.