Egypt's Ali Farag stunned home hopeful Nick Matthew in round two at the British Open in Hull.
England's Matthew, a three-time champion at the event and a triple world champion, suffered his worst result at the Professional Squash Association (PSA) World Series event since 2002.
In a topsy-turvy encounter, world number 14 Farag wrapped up a 4-11, 13-11, 10-12, 11-7, 11-4 success.
Matthew's cause wasn't helped by an ankle injury suffered in the fourth game.
"I knew he wasn’t at his best towards the end of the fourth but I am glad it didn’t get into my head and I was able to carry on playing my game,” said Farag, who progresses to the quarter finals.
"I can’t put it into words how good it feels to get through to the quarter-final.
"I don’t want to be satisfied yet, I want to keep progressing until the following round until I win it.
"It might not happen this year but maybe the year after and I will definitely come every year and do my best to win it."
Ramy Ashour, who is also a triple world champion, saved a match ball before beating Australia's Ryan Cuskelly, his sparring partner, 11-5, 11-9, 6-11, 9-11, 13-11.
The match lasted for 106 minutes, the second longest of Ashour's career.
World champion Gregory Gaultier of France was comfortable against South Africa's Stephen Coppinger, 11-5, 11-1, 11-9.
German Simon Rösner is also through after beating England's Chris Simpson in another epic, 11-8, 10-12, 10-12, 11-7, 11-4.
In the women's competition, Malaysia's eight-time world champion Nicol David reached the quarter-finals by coming past Australian Donna Urquhart 11-4, 11-7, 11-6.
Egyptian Nour El Sherbini and Omneya Abdel Kawy are also safely into the next round.
El Sherbini beat Liu Tsz-Ling of Hong Kong 11-3, 11-7, 6-11, 11-1 with Kawy seeing off another Hong Kong player, Alison Waters, 11-8, 11-2, 11-3.
American Amada Soby also went through by beating England's Alison Waters 11-8, 11-2, 11-3.