Mark Allen succeeded where fellow countrymen Joe Swail and Gerard Green failed at the Waterfront Hall last night.

The Antrim potter came through his second round clash with Dominic Dale 5-4 and now faces another Welshman in Mark Williams in the last 16.

Twice World champion Williams caused one of the upsets of the tournament to date when he ousted another former Crucible champion in Shaun Murphy.

Murphy wend down 5-2 to Williams, who has slipped down the rankings.

The Rotherham professional, a world champion in 2005, mustered a high break of just 37 as Williams progressed having pocketed breaks of 50, 85, 50, 48 and 44.

Allen was made to sweat though for his victory as Dale staged a late rally to level the match at 4-4 but he held his nerve to scrape through.

Defending champion Stephen Maguire wasted little time in progressing to the last 16.

The world number two thumped Nottingham qualifier Michael Holt 5-1 and outlined his plans to become the first professional for three and a half years to make a successful defence of a ranking title.

World champion Ronnie O'Sullivan is the last player to have achieved the feat, having won the Welsh Open in 2004 and 2005.

"I was scared of my first match, that's the first time I've felt pressure since the World Championship," admitted the Glaswegian.

"It was always going to be a tough match playing Michael, but I didn't expect to win 5-1.

"Although it was 5-1 there were three frames decided on the black ball, so winning them was massive.

"I've not had the heart going like that for a while. You never forget it, but when it comes back it's quite scary, you realise you're under some pressure.

"I'd love to retain my title here this year, I've got so many fond memories of winning here last year."

Maguire compiled breaks of 55, 96, 58, 40 and 127 to go through - and will now play Alan McManus in the next phase.

Preston's Ian McCulloch booked his last 16 place with a 5-2 win over Neil Robertson, while Dave Harold fought back from 3-1 down to beat Graeme Dott, the 2006 world champion, 5-3.

Results: Stephen Maguire (Sco) 5 Michael Holt 1 (Eng); Neil Robertson (Aus) 2 Ian McCulloch (Eng) 5; Graeme Dott (Sco) 3 Dave Harold (Eng) 5; Shaun Murphy (Eng) 2 Mark Williams (Wal) 5; Peter Ebdon (Eng) 0 Liang Wenbo (Chi) 5; Mark King (Eng) 3 Alan McManus (Sco) 5; Mark Allen 5 Dominic Dale 4.