World and Olympic champion Lin Dan of China lost his All England title on Friday night, downed in a major upset 21-16 18-21 21-17 by sixth-seeded compatriot Bao Chunlai in the quarter-finals.
Lin has contested the last six All England Badminton finals, winning four of them, but had no answer to his fellow left-hander.
Seeded two - behind Lee Chong Wei of Malaysia, who now looks clear favourite to land his first All England title after his rival's exit - Lin looked to be on his way to victory in the decider when he led 11-7 but a losing run of six points in succession turned the tables.
A confident Bao raced to 20-15 with some stunning winners and although Lin saved two match points, a smash down the line that was just out handed victory to his opponent.
Lin had been making his seasonal debut in the tournament after missing the first two Super Series of the year but has looked in good shape.
"Bao was playing really well today but I was okay too. I thought I had a chance," he said.
Bao said: "I can't remember the last time I beat him. I played really, really well. I played a faster game which I think gave me the edge."
Bao's opponent in Saturday's semi-finals is unseeded Japanese Kenichi Tago who ousted third seed Chen Jin of China, champion in 2008, 22-20 19-21 21-13. Tago became the first Japanese in 40 years to reach the men's singles semi-finals.
The other semi-final features world No 1 Chong Wei against Denmark's Peter Gade, All England champion back in 1999.
Chong Wei was stretched by South Korean qualifier Shon Wan-ho before emerging a 14-21 21-14 21-14 winner.
Gade, meanwhile, came through in one of the longest matches of the week. The two stalwarts never let each other out of sight before Gade edged out former Olympic champion Taufik Hidayat of Indonesia 20-22 22-20 22-20.
"I knew if I could keep moving him at a fast speed I had a chance," the Dane told reporters. "Mentally, it was one of my best games ever so I am really happy."
Remarkably, when Gade won his All England title 11 years ago his opponent in the final was Hidayat, then 17. "He was just a boy," quipped the Dane, now 33, when asked to recall the match.
In the women's singles, Dane Tine Rasmussen, All England champion in 2008, saved three match points before rallying to beat world champion Lu Lan of China 16-21 23-21 21-11 in their quarter-final.