CANBERRA (AFP) - Australian veteran David Palmer pulled off a major upset when he downed world number three Karim Darwish to reach the semi-finals of the Australian Open squash championships in Canberra on Friday. Palmer, 35, playing with an injured ankle, came out firing in the first game then held off a comeback from the Egyptian to win 11-3, 12-10, 8-11, 12-10. It was his eighth win over Darwish but his first since 2008 and ensures a semi-final against world number one 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 Darwish to the delight of the parochial fans in Canberra's Royal Theatre. The Australian number one 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 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," he admitted 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."