Australia's David Palmer showed he's still a major force in the world of squash when he stunned world number three Karim Darwish to reach the semi-finals of the Viridian Australian Open, the third PSA World Series event of the year in Canberra.

Palmer, at 35 and playing with an injured ankle, came out firing in the first game then held off a comeback from the third-seeded Egyptian to win 11-3, 12-10, 8-11, 12-10.

It was Palmer's eighth win over Darwish - but the Australian number one's first since 2008, and ensures a semi-final against world number one Nick Matthew of England.

Matthew earlier withstood a fierce onslaught from Dutchman Laurens Jan Anjema to win 11-5, 11-9, 7-11, 11-5 and move a step closer to defending his title.

But he will first have to get past Palmer, who played brilliantly against the 29-year-old former world number one from Cairo to the delight of the partisan fans in Canberra's Royal Theatre.

Palmer, ranked 10 in the world, injured his ankle in his opening round match and there was some doubt as to whether he would be able to continue in the tournament.

He was slightly tentative in his second round win over England's Tom Richards, but showed no signs of discomfort as he took advantage of an at times out-of-sorts Darwish to record the tournament's biggest upset.

"I didn't really expect it," admitted the former world number one and two-time world champion later. "I can't give much up to these guys at the best of times but I've struggled all week with my ankle and somehow I'm managing to get through.

"Maybe it's good because I'm trying not to put too much pressure on myself, just trying to get through the match without reinjuring it and trying to make it at least competitive. Maybe being a bit more relaxed is working," added one of the Tour's oldest competitors.

Palmer said he would take that attitude into the semi-final against Matthew.

"I've got nothing to lose, it's a dream to be able to play a major semi-final here in Australia," he said. "There's a bit of rivalry with Nick but then again he's the one with the pressure on him. I quite like playing against him, so if I'm up for it, who knows?"

Matthew survived a brutal onslaught from Anjema, taking an early lead then holding off a ferocious comeback from the tall left-hander.

The six-time Dutch champion came into the quarter-finals in top form, having upset seventh seed Thierry Lincou in the first round before demolishing American Julian Illingworth in the second.

However, he started slowly allowing Matthew the early advantage before finding his way back into the match.

Both men played some spectacular squash as the momentum swung between the two.

The Dutchman took an early lead in the fourth as he looked to get the match back on even terms, only for Matthew to claw his way back and eventually ease away with the game to close out the quarter-final.

"He came back strong, he obviously played well in the first round and had one of the best wins of his career and then backed up really well in the second round," Matthew said.

"I felt before the match that little buzz that I've not had this week. I felt that I was up for a big match and I started really well. I scrapped really well - if things are not going well that's one thing I can rely on, to scrap hard and fight for every point."

Crowd favourite Gregory Gaultier of France overcame a slow start to down fourth-seeded Englishman James Willstrop 7-11, 12-10, 11-4, 11-5.

Willstrop came out firing and had Gaultier in all sorts of trouble, but the lower-ranked Frenchman worked his way back into the game and finished far stronger than his opponent.

"At the beginning it was just torture for me - he made an unbelievable start and I couldn't do anything," Gaultier said.

"I just told myself to forget about it and fight hard. Today was not a day for accuracy from me, so I thought to myself 'try and raise the pace and things may work out your way'."

Gaultier will take on Ramy Ashour in a repeat of last year's classic semi-final.

Ashour, the world number two from Egypt, also overcame a slow start before storming back to beat England's Peter Barker 5-11, 11-9, 11-4, 11-4.

RESULTS: PSA World Series Viridian Australian Open, Canberra, Australia

Quarter-finals:
[1] Nick Matthew (ENG) bt Laurens Jan Anjema (NED) 11-5, 11-9, 7-11, 11-5 (68m)
David Palmer (AUS) bt [3] Karim Darwish (EGY) 11-3, 10-12, 11-8, 12-10 (60m)
[5] Gregory Gaultier (FRA) bt [4] James Willstrop (ENG) 7-11, 12-10, 11-4, 11-5 (69m)
[2] Ramy Ashour (EGY) bt [6] Peter Barker (ENG) 5-11, 11-9, 11-4, 11-4 (42m)

Semi-final line-up:
[1] Nick Matthew (ENG) v David Palmer (AUS)
[2] Ramy Ashour (EGY) v [5] Gregory Gaultier (FRA)

Official event website: www.australiansquashopen.com