Stuart Bingham became the third former or current world snooker champion to go out in the first round of this year's championships as he was beaten 10 frames to seven by qualifier Jack Lisowski.
Another former world champion, Australia's Neil Robertson, is also in trouble, the 2010 winner trailing English journeyman Robert Milkins 6-3 ahead of the concluding session on Wednesday.
Milkins, 42, could be on course to repeat what is probably the finest performance of his career as he beat Robertson at a similar stage in the 2013 edition.
Bingham joins defending champion Mark Selby and 2005 world champion Shaun Murphy as big names to have failed to get over the first hurdle.
The trio's departures will boost the chances of the likes of quintuple champion Ronnie 'Rocket' O'Sullivan and Chinese star Ding Junhui, who are both safely into the second round.
Lisowski never faltered after taking only a one-frame lead, 5-4, into the final session in what is only his second appearance at The Crucible Theatre in Sheffield.
The 26-year-old Englishman, who went out in the first round on his debut in 2013, displayed the kind of form that saw him reach the semi-finals of The Shanghai Masters last year.
Bingham kept snapping at Lisowski's heels but the latter went from 7-6 up to win two frames in succession and although his opponent made it 9-7 the world number 30 kept his nerve to seal his place in the second round.
"It was a great win for me," said Lisowski.
"Stuart's won this tournament before and is one of the best players in the world, so to come here and win after five years ago being so disappointing, it shows that my game has improved.
"It’s such a tough setup to play in if you're not used to it, but five years have passed and I was able to cope with it a lot better this time."
Lisowski will play the winner of the clash between Scotland's quadruple world champion John Higgins and Thailand's Thepchaiya Un-Nooh which gets underway later on Wednesday.