Snooker: O'sullivan Must Beat Demons to See Off Ding

Should Ronnie O'Sullivan beat Ding Junhui in the first round tomorrow it is likely he will go on to lift the world championship for the third time on May 7. O'Sullivan, though, has been so volatile in the past two seasons that he comes to Sheffield not having won a world-ranking title for 25 months.

He has won three invitation events this season, the Betfred Premier League, a series of one-night stands in front of capacity crowds, the Kilkenny Masters, which occupied him for only three days, and the Masters, for which he could commute for his four matches from his Chigwell home. But his restless temperament has been struggling to cope with the long haul of ranking tournaments, particularly overseas.

Some of his shot choices in the China Open, notably in his semi-final defeat to the world champion, Graeme Dott, three weeks ago, suggested an indifference to losing; his psychological collapse against Dott in last year's semi-final at the Crucible was poignant to witness; and his walkout in the sixth frame of his UK Championship quarter-final in December remains unexplained and is the subject of a disciplinary process which has been put on hold until after the championship.

"Ronnie's had these demons in his head for years," his manager, Lee Doyle, said. "Sometimes, when he gets a real low, nothing matters."

These recurrent depressions date from his father's imprisonment for murder in 1992, likely to last until 2010. Along this long and lonely road O'Sullivan, now 31, has sampled everything from drugs to hypnosis but his most effective therapies appear to be his passion for running and his domestic life with Jo and their infant daughter. Amid his turmoil is the knowledge that he is the greatest talent ever to play the game. "When he's on song he makes everyone else look a carthorse," said Steve Davis.

O'Sullivan's love of snooker is not in doubt but no one can be quite sure how he will feel when he plays Ding over two afternoons, tomorrow and Monday.