Ken Doherty qualified for the quarter-finals of the Scottish Open in Aberdeen last night thanks to a 5-3 victory over Fergal O'Brien.

As expected it was a gruelling contest between the two friends and practice partners, with Doherty clinching a match today against Welshman Mark Williams.

"It will be a very different game against Mark, and that's the type of match I prefer," said Doherty.

Earlier, Glaswegian Graeme Dott caused the upset of the third round, coming from 4-2 down to beat 1991 world champion John Parrott 5-4.

Stephen Hendry was less than impressive in defeating Brian Morgan 5-3 and claims he will be the underdog tonight when he meets Nations Cup team-mate Alan McManus for a place in the semi-finals. McManus beat another Scottish cueman, Chris Small, 5-0 last night.

"It's usually a case of the other Scots raising their game against me," said Hendry as he became one of four Scots through to the quarter-finals.

"But at the moment they're having more success than I am. So, if I want to get any further I will have to raise my game against Alan."

McManus played some superb snooker to whitewash Edinburgh rival Small. "That's as well as I've played for a long, long time and the heaviest I have scored for ages," said the world number eight.

McManus allowed Grand Prix semi-finalist Small just 47 points. In contrast he made breaks of 95, 101, 60 and 83 as he totalled 486 in reply.

John Higgins made it to the quarter-finals with a 5-1 success over Dave Harold, the world number 19 from Stoke.

The world champion and world number one said: "I missed a couple of balls but I was delighted with the way I played."

Higgins, still going strong after his Masters triumph at Wembley, meets Grand Prix champion Stephen Lee in the second quarter-final.

"Stephen beat me in the Irish Open, so I know it won't be easy. But I can't play much worse than I did in Dublin," he said.