Ronnie O'Sullivan will begin his defence of the world title at Sheffield's Crucible Theatre on April 20 like he did last year - as a first-fence faller at the Regal Scottish Open.

The world and UK champion's 5-3 defeat by Barry Hawkins, a 22-year-old left-hander from Sydenham, showed him in one of his lower moods. His performance, full of surprising errors as it was, was not entirely uncaring even if he did not appear unduly bothered by the prospect of defeat which quickly developed.

His press conference was monosyllabic but his temperament is so volatile that his attitude may be entirely different for his world title defence.

O'Sullivan won six events last season and over the two-year performances on which the official rankings will be revised on May 7, long seemed certain to be the official No1.

However, Mark Williams, who started the season top, could be top again. His back-to-back China Open and Thailand Masters titles last month have brought him within striking distance and he is still involved here.

Hawkins, a quarter-finalist in the LG Cup in Preston in October, has risen from his start-of-season 85th to a provisional 55th in the rankings and in the round which reduced Aberdeen's 48 starters to 32, showed his quality by making four breaks over 70 in turning his 3-1 arrears against Marco Fu, the world No17, into a 5-3 victory.

He was assisted to a 3-1 lead yesterday by two gimmes, O'Sullivan not requiring him to pot the frame-ball pink in the second frame or the frame-ball last red in the fourth.

After Hawkins had faltered on 65 in the fourth, O'Sullivan addressed himself to attempting a winning clearance but, on 31, was unable to obtain position on the awkwardly situated last red and played a truly dreadful safety shot.

O'Sullivan, who has won only one tournament this season, did recover to 2-3 with a run of 65 but Hawkins stroked in a long red from which he made 93 to lead 4-2 and capped O'Sullivan's score list two frames later to progress to the last 16.

Hawkins was, predictably, "over the moon. I can't believe it. Even if [top players] aren't playing well you've still got to pot the balls".

A few years ago, he had become sceptical of making a living from snooker. He applied for several office jobs but, having insufficient academic qualifications, never secured one.

"Perhaps this was a blessing in disguise," he said after his win had sent his earnings for the season to £40,406.

Two other members of the top 16 were eliminated. Paul Hunter, winner of the Regal Welsh Open and Benson & Hedges Masters this year, was beaten 5-3 by the Welsh No3 Dominic Dale; Joe Swail, the world No10, was a 5-3 loser to the Republic of Ireland No3 Michael Judge.

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