Defending champion Mark Williams suffered a shock first-round defeat to Stephen Lee at the China Open, losing 5-4 despite making four centuries.
The Welshman rallied from 3-2 down to lead 4-3 but Lee took the last two frames, wiping out a 70-11 deficit in the decider with a 61 to seal victory.
Williams, the world number two, had breaks of 137, 133, 104 and 100 but could not shake off the dogged Lee.
Four of the world's top 16 players were knocked out in a day of shocks.
"Mark played some terrific stuff and I was happy just to get to 4-4," said Lee, "but the clearance in the last was very special and brought back a lot of confidence.
"I had a great run when I cleaned up and it's great when you treat the crowd to that.
"At times I looked helpless and anyone would have as Mark played some terrific snooker - every time he got to the table it seemed there was a century break."
Williams said: "I played well enough and can't grumble as Stephen made a great dish-up to win the match. It's not often you get four tons and lose and I played well but I can't do much about it.
"He just won the scrappy frames and I was unlucky in two of them. It's always nice to play in good conditions and the table was lovely, I just got beat.
"If I'd had a good run here then I would've ended up as world number one but now it's up for grabs in the World Championship."
Stephen Maguire, ranked seven in the world, lost 5-3 to Mark Davis. With the game finely poised at 3-3, Davis stepped up a gear with runs of 73 and 137 to clinch victory.
Maguire's fellow Scot Graeme Dott also bowed out after losing a final-frame decider to Li Hang of China.
The former world champion, who won this event in 2007, came back to level from 4-2 down, but Li held his nerve to book his place in round two.
World number 11 Mark Allen also went the distance before losing out to Scotland's Marcus Campbell, winner of the Euro Players Tour Championship in October.
Ding Junhui, who won the China Open in 2005, produced the comeback of the day after recovering from 4-1 down to beat Norway's Kurt Maflin, while Shaun Murphy, runner-up to Stephen Maguire here three years ago, defeated Joe Perry 5-3.
Elsewhere, Northern Ireland's Gerard Greene and Robert Milkins of England both won their wildcard matches against Chinese opponents. Greene overcame Yu Delu 5-2 while Milkins beat Rouzi Maimaiti 5-1.