Ken Doherty beat Ronnie O'Sullivan 5-2 to reach the semi-finals of the £295,000 Rothmans Grand Prix in Malta last night, bouncing back impressively from his defeat in the Benson and Hedges Masters final and the missed opportunity of a 147 break.

It was Doherty's first victory over O'Sullivan in a ranking tournament since the 1994 UK Championship. After that match O'Sullivan threatened to quit the game, but yesterday he reacted only with heavy irony.

"I'm dumbstruck I can play so well and lose," said O'Sullivan, whose best breaks were only 45, 33 and 30. "I thought I played out of my skin. No-one really made a mistake. Ken played superbly and I thought I was excellent as well."

Doherty did, however, play well, capitalising on his opponent's frequent errors.

"It's a great result to beat a player of Ronnie's calibre," Doherty said. "I managed to punish his mistakes while also making some good breaks.

"I feel confident of scoring heavily and finishing off frames in one visit - which has been lacking from my game for a while.

"But I've never given up hope even when some people have had their doubts."

Doherty cued superbly to take a 2-0 lead with breaks of 105 and 58. He lost the next two frames as O'Sullivan briefly rallied, but O'Sullivan missed an easy red to the middle in the fifth frame when poised to take the lead and Doherty regained control.