Holder Viktor Axelsen said that he made "way too many mistakes" as the giant Dane was dumped out of the badminton World Championships quarter-finals on Friday by China's Chen Long.
The top-ranked players in both the men's and women's draws are now out, after Taiwan's Tai Tzu-ying was beaten earlier in the day in Nanjing by another Chinese.
Olympic champion Chen will play Shi Yuqi -- at three the top remaining seed -- in an all-Chinese semi-final following his emphatic 21-19, 21-11 victory over Axelsen.
There was a moment of controversy and the first game was held up for two minutes as the 29-year-old Chen disputed a call that fell in favour of the Dane.
But the 24-year-old world number one Axelsen, who has single-handedly broken Asia's stranglehold on men's badminton in the last year, was always playing catch-up.
"He was a lot better than me today, unfortunately," said Axelsen, who tossed his racquet spinning into the air after losing the first game, drawing a withering look from the chair umpire.
"But life goes on and I have to learn from this."
The other men's semi-final will be between Liew Daren, the unseeded Malaysian, and in-form Kento Momota of Japan, now favourite for the title after Axelsen's demise.
Liew defeated Japan's Kanta Tsuneyama over three gruelling games despite hurting his right ankle.
An overcome Liew collapsed to the floor at the end with his arms covering his head and his face planted in the court.
- Shouting into the semis -
Olympic champion Carolina Marin bellowed and blustered her way into the women's semi-finals with a devastating victory over India's Saina Nehwal.
The 25-year-old Spaniard is chasing a third world crown and on this form could well get it.
Marin plays China's He Bingjiao after the sixth seed stunned Taiwan's Tai.
Marin destroyed Nehwal, who cut a demoralised figure by the end of a 21-6, 21-11 mauling.
The Spaniard is particularly vocal and demonstrative on court, shouting or screaming in Spanish after every winning point and before serving too.
One member of the audience took to imitating her.
Asked by AFP what she was hollering, Marin replied with a laugh: "I cannot tell you!
"It is just something I keep to myself. It was not a strategy against Saina, it is something I do against any opponent. I do it for myself.
"I learnt to do this some years ago, it was not something I did from the beginning of my career, that's impossible because I was too young.
"I had to learn many things in my career, and this is one thing I learnt."
Nehwal, a former number one who looked shell-shocked afterwards, said that she had no complaints about Marin's behaviour.
The strongly fancied Tai tasted just a second defeat in 35 matches, a remarkable run which brought five titles and had made her the woman to beat in Nanjing.
But the 24-year-old was sloppy at times against He, making a series of errors at the net and going out of the tournament 21-18, 7-21, 21-13.
The other last-four clash in the women's draw tees up second seed Akane Yamaguchi of Japan against India's P.V. Sindhu.
Sindhu, seeded three, claimed the scalp of reigning champion Nozomi Okuhara of Japan.
Spaniard Carolina Marin, who is particularly vocal and demonstrative on court, is chasing a third badminton world crown