Snooker: One sequence last night typified the increasingly despairing nature of Ken Doherty's World Championship semi-final match against Paul Hunter.

At 41-44 down in the 20th frame and trailing 12-7, Doherty had, after a series of low-break skirmishes, placed himself perfectly for a colours clearance and the frame. It should have been a basic sequence of plays. Potting the green, too much screw brought the white off position for the brown. Using the rest, Doherty missed the pot, Hunter arrived to clear and in went the players for the mid-session interval, Doherty chasing 7-13 instead of 8-12.

Another uncharacteristic play in the 22nd frame saw Doherty attempt a simple safety shot behind the yellow from an inch away. He left it short and fouled. This time there was no plaster under the baize.

When Doherty needed Hunter to sit too long, think too much and hunger for the floor, too often he handed him the spotlight. On a night when he needed to own the table, he stood aside for the 24-year-old fifth seed. It was a frustrating day for the 1997 champion.

But Doherty survived to bring this match to a final session. He is still doggedly chasing but has been deeply wounded by Hunter and steps into the theatre today 15-9 down with nine frames remaining. Hunter needs two frames to win.

It was the early session yesterday morning where Doherty needed to begin to claw back ground against his younger opponent and seek to take Hunter to places in his head that he had never been before at this stage of The Crucible. That required Doherty to draw close enough for the less experienced player to feel warm breath on his collar.

For two opening frames the Irishman's attempts to do just that looked sharply effective as he kept Hunter seated for 6-3 before clearing for the first century of the semi-final, a 111, for 6-4. It was an ideal second leg start, and when Doherty went 10 points ahead in the third frame of the session, it seemed certain that he could, in one surge, haul himself right back into the match.

But frustratingly the 33-year-old, although showing signs of developing breaks, crucially failed to keep the heat consistently intense. A missed short-range black started the slide, Hunter coming in with a half century clearance for 7-4.

Again in the 12th frame a straightforward brown refused to drop for Doherty's second unforced error, and suddenly he began to look imperfect, slightly jaded. Clearly Doherty was disgusted with his punishing lapse knowing that Hunter would again thank him by taking the frame, which he did with a 135, the third highest break of the tournament and the ninth seed's seventh century at The Crucible.

Although Doherty replied with 115 for 9-5, Hunter regained his early match momentum with an 85 for 10-5, while Doherty continued with his friendly fire damage, this time an over-cut black and a missed red to the corner handed Hunter his perfect 11-5 platform.

Despite the six-frame cushion Hunter held going into the evening session, Doherty opened with a 92 break for 11-6. Realistically he badly needed to eat into Hunter's lead, not simply share the remaining frames. But Hunter again came in when Doherty broke down at 59 to hoover up the balls up with 75 for 12-6, and when Doherty won the 19th frame after a series of safety plays and fractured breaks, it was again Hunter who hopped on his error on the brown for 13-7.

Taking the 21st frame for 13-8 insured a final session today and kept at bay the ignominy of Hunter finishing the match well inside the distance. But by the look of Doherty's body language, he knows more than anyone that the frequency of chances he has being offering Hunter can't continue. Ladbrokes have Doherty going on to claim a second title at 40 to 1, with Hunter at 7 to 4.

England's Stephen Lee fought to within four frames of the world number one Mark Williams in the other semi-final and now trails 10-6. Williams, who went into the second session 7-1 ahead, lost four consecutive frames for 7-5 before gathering himself to rattle off three in a row for 10-5. Lee snatched the final one of the day.

Paul Hunter (Eng) leads Ken Doherty (Ire) 15-9 (Doherty first): 33-66 13-93 71-0 32-67 33-90 70-62 43-57 30-73 94-0 115-20 10-111 12-75 0-139 115-0 4-84, 52-67, 92-0, 59-75, 77-34, 41-59, 59-22, 67-56, 19-75.

Mark Williams (Wal) leads Stephen Lee (Eng) 10-6 (Williams first): 65-61 113-19 (Williams 102) 62-47 69-39 74-33 61-32 4-140 (Lee 140) 95-0 0-74 19-61 36-64 25-65 125-0 67-64 78-4 0-133.

Matches completed today.