Welshman Mark Williams became the fourth top-10 player to crash out in the first round of the UK Championship after a shock 6-3 defeat to Mark King.
Williams, the world number five, lost five of the first six frames and though he won the next two, King won a scrappy ninth frame to clinch victory.
Williams follows world number one Judd Trump, Mark Allen and Ding Junhui out of snooker's second biggest tournament.
Australian Neil Robertson made four centuries as he beat Tom Ford 6-1.
Williams, who has reached the UK Championship final just once since he claimed his second title in 2002, said: "I was terrible. Shocking. I felt all right going in but I couldn't pot three balls on the trot.
"The table was beautiful, there was a good crowd, everything you could want. It's getting boring for me to say how badly I am playing."
World number 32 King added: "I played pretty solid and you take whatever you can get. I made a 50-odd and made a century and I'm happy."
King will play Belgian Luca Brecel, who became the youngest player ever to play at the Crucible earlier this year, after the 17-year-old beat world number 12 Ricky Walden 6-5 to secure his first major win on the professional tour.
The world number 74 found himself 2-0, 4-2 and 5-4 down, but kept his composure to force a decider and then close out an impressive win.
Matthew Stevens beat fellow Welshman Dominic Dale 6-1 to set up a second-round match with Marco Fu of Hong Kong.
Robertson, who is aiming to win the UK Championship at his 11th attempt, will take on England's Barry Hawkins in the next round.
"I felt mega-confident today," said Robertson, who won the world title in 2010 and is the current Masters champion. "Practice has been going very well and I've got a good record against Tom.
"When I have played him previously I think it's been 6-0 and 6-1 and I knew if I could get on top of him early on then it would be tough for him."
Robertson, who is trying to become only the eighth player to win the UK, Masters and world titles, added: "There are still some great players left in the tournament.
"But for me, it would be fantastic to hold the Masters and win the UK, that would be a special feeling. I have the opportunity to do that and to win all three in a short space of time would be great."