Clearly in considerable pain, Egypt's former champion Ramy Ashour was forced to concede his match in today's quarter-finals of the PSA World Open to allow sixth-seeded Frenchman Gregory Gaultier through to his fourth semi-final in six years at the New Luxor Theatre in Rotterdam.

There was no hint of what was to come in a fast and attacking evenly-contested first game. To the obvious delight of the crowd, Gaultier edged ahead to go one game up. But the second was entirely different as world No2 Ashour was suddenly almost immobile on the court - with the Frenchman serving the game out in just three minutes.

It was after just a single point in the third that the visibly distressed Egyptian, seemingly suffering with a hamstring injury, signalled the end of the match with the score at 11-8, 11-1, 1-0.

Gaultier moves on to face England's James Willstrop after the fourth seed made up for failing to close out two match-balls in the third game by beating Egypt's four-time world champion Amr Shabana 11-8, 11-2, 11-13, 11-1.

"To lead Shabana 2/0, you can get a little bit excited - but you don't really know where his head's at," explained the 28-year-old from Leeds afterwards. "Obviously he's been everywhere and there's nothing he hasn't done but you can't carried away. I knew that physically from 2/0 it's a massive boost.

"But massive credit to him to come out and do what he did. But I knew that if I kept pushing and pushing that I would get a few more chances.

"In Kuwait, we played in the World Open and he never relented physically at all. Everyone talks about his shots, but I think he's very underrated for the physical part of his game. If he needs to rally he will do.

"It's extremely pleasing to beat him in a big event. Everyone knows what a player he is. I'm feeling good and looking forward to the semis."

A significant moment in the history of the sport came earlier in the day when, after losing to Egyptian rival Karim Darwish, illustrious Australian David Palmer confirmed his decision to retire. The 35-year-old from New South Wales, winner of the world title in 2002 and 2006, had reached his seventh quarter-final since 2002 after a gruelling 96-minute five-game victory over French rival Thierry Lincou.

But third seed Darwish was too strong, winning 11-9, 11-7, 11-1 in 42 minutes.

"He was a little bit too good today," said Palmer, whose career summary includes 27 PSA World Tour titles (including 4 British Opens) from 55 final appearances. "It was my first match on the glass unfortunately - it would have been nice to get an early match on here, just to get a feel for it. But I thought I played ok.

"I needed that first game - I needed a good start to try and create pressure. He didn't make any mistakes today either, he didn't give me anything. Every point I won I had to really earn - and I think he realised he had a good game plan against me.

"But overall I'm happy," added the winner of six Commonwealth Games medals (two silver and four bronze) over three Games. "It's a great way to finish my career and I'm happy to make another quarter final - and at 35, I don't think it's a bad effort!"

"I have no regrets in my career really. Apart from maybe a gold medal at the Commonwealth Games - that's the only thing missing. Apart from that, I'm very proud of what I've achieved. Obviously I've left a few titles out there that I could have won, but I've won a couple of close ones too so it's evened out over my career I think."

Darwish now takes on top seed Nick Matthew. But the defending champion dropped the first game to seventh seed Peter Barker before beating his England team-mate 6-11, 11-8, 11-8, 11-5 in 71 minutes.

"Pete has come on tremendously in the last year," said the 31-year-old from Sheffield. "He's been knocking on the door of the top for a while now. Maybe his injury this evening took it out of him a bit in the fourth, but we had three really tough games out there today.

"I didn't play badly in the first - he was just playing a bit better than me. He was varying the pace and his length and width were immaculate. But I came through that patch mentally and was able to change things a bit and turn the screws on him at the end of the second.

"He didn't then disappear in the third either - a year or two ago he'd have faded there, but he stuck in and showed the improvements that he's made over the last year.

"Karim's looking good - he's not dropped a game yet, I don't think, so I'll have to play better tomorrow."

RESULTS: PSA World Open, Rotterdam, Netherlands

Quarter-finals:
[1] Nick Matthew (ENG) bt [7] Peter Barker (ENG) 6-11, 11-8, 11-8, 11-5 (71m)
[3] Karim Darwish (EGY) bt [8] David Palmer (AUS) 11-9, 11-7, 11-1 (42m)
[4] James Willstrop (ENG) bt [5] Amr Shabana (EGY) 11-8, 11-2, 11-13, 11-1 (59m)
[6] Gregory Gaultier (FRA) bt [2] Ramy Ashour (EGY) 11-8, 11-1, 1-0 ret. (24m)

Semi-final line-up:
[1] Nick Matthew (ENG) v [3] Karim Darwish (EGY)
[6] Gregory Gaultier (FRA) v [4] James Willstrop (ENG)

More information can be found on the official tournament site www.worldopensquash2011.com

For all the latest Tour news: www.psaworldtour.com