Malaysia's world number one Lee Chong Wei exited the world badminton championships on Friday, beaten 21-15, 11-21, 21-12 in the quarter-finals by former World and Olympic champion Taufik Hidayat.
Less than an hour later, in another big surprise, title-holder Lin Dan succumbed 21-13, 21-13 to 13th seeded South Korean Park Sung-hwan.
Lin won the world title in 2006, 2007 and 2009 and the Olympic gold medal in Beijing in 2008 when there was no World championship.
Park told a media conference: "I've gone to the next level in badminton with this result."
The run of upsets continued when India's Saina Nehwal, seeded two in the women's singles, suffered disappointment when she lost 21-8, 21-14 to Chinese sixth seed Wang Shixian.
"I was trying to be more quick around the net but somehow my movement was very, very slow and I was feeling too tired today," said Nehwal.
Chong Wei's defeat continued his poor record at world championships and Olympic level but confirmed Hidayat's renaissance after slipping in the rankings in recent years.
The Malaysian top seed went into the match on a high after some fine displays in earlier rounds and with a 9-5 career head-to-head against his fifth-seeded Indonesian opponent.
But a nervy start handed Hidayat the advantage with Chong Wei's touch at the net unusually suspect. He rallied a little from 9-15 to 12-15 but after that it was Hidayat's game.
Chong Wei was more of his old self in the second set but nerves returned in the third. Some hesitancy round the net was compounded by a service fault, a rare error in badminton.
He led 8-5 and 10-8 but once Hidayat squared at 12-12 it was downhill all the way for the unhappy Malaysian.
Malaysia have never won a gold medal at a world championships, singles or doubles, since the tournament was inaugurated in 1977.
The pressure on Chong Wei has shown at similar big tournaments but his cause on Friday was not helped by a back problem sustained on Thursday.
"It's quite painful," he told reporters. "I felt better when I woke up this morning but I pulled it again during the match."
The Malaysian was clearly disappointed to lose out again but promised: "I'll try again next year."
Modest Hidayat, 29, put his win down to luck, saying: "I feel good both physically and mentally.
"Chong Wei wants the world championship because he's never got the big title, only the Super Series and the All England. But he's still young and can wait until next year."
Malaysia still have a chance of gold thanks to their top seeded pair in the men's doubles, Koo Kien Keat and Tan Boon Heong.
They battled past seventh-seeded South Koreans Jung Jae-sung and Lee Yong-dae 23-25, 21-13, 21-14 to reach Saturday's semis.
"We were playing our own game and able to attack more," a relieved Kien Keat told reporters.