Australian David Palmer, bidding for a fourth British Open title, will meet Englishman James Willstrop in the final of the world's most famous squash tournament.

Palmer defeated Egypt's Karim Darwish in the semi-finals here on Sunday, a day after shocking world No.1 Amr Shabana.

Palmer and Darwish were locked at one game apiece when the Egyptian suffered an Achilles injury while leading 8-3 in the third.

The 31-year-old Palmer, from Lithgow in NSW, said that after a blazing start he had fallen into the trap of playing a style of game that Darwish enjoyed.

He added that although he had adjusted after Darwish had raced to an early lead in the third, he conceded he had been fortunate when his opponent was forced to retire.

"In the first game I was playing particularly well, but I thought he was very slow," Palmer said.

"Then it sort of turned round in the second - I lost my length, got slow and he started playing extremely well.

"If you go short against an Egyptian, he'll punish you, and that's exactly what happened.

"I started to get worried a bit with the speed Karim was running away with it.

"I was still relaxed and focused, which is essential in my game, and we started to string a few long and better points at the end, but still, I would have had to work very hard to get myself out of trouble."

Making the final is a triumph for Palmer, who has slipped from No.2 to No.6 in the world rankings this year as pundits speculated he would no longer challenge for major titles.

He moved to Boston from his previous training base in Belgium and no longer has daily contact with coach Shaun Moxham, resulting in a number of early round exits in recent tournaments.

"I'm feeling good physically, I'm glad that I've gone back to my old hard training," he said.

"We spoke a lot with Shaun and I've worked on both the physical and the mental side to make sure I believed that I could win these kind of tournaments again.

"I feel a bit strange, but very happy to be in the final for the fourth time."

Palmer will have his work cut out against world No.3 Willstrop, who looked impressive during his 11-7 11-3 11-7 win over Frenchman Thierry Lincou.

The women's final will be between world No.1 Nicol David of Malaysia and England's Jenny Duncalf.