Eight-time and defending champion Ronnie O'Sullivan crashed out on the opening day of the UK Championship after a 6-4 defeat to Barry Hawkins in York.
Hawkins reeled off four frames in a row to haul back a 4-2 deficit and clinch only his third win over O'Sullivan in 21 career attempts.
It was a remarkable revival by the 45-year-old, who compiled four consecutive half-centuries that left his illustrious opponent stuck in his seat for three straight frames.
"I just think Barry played a good match and deserved his win, so you have to give all credit to him," said a clearly disappointed O'Sullivan shortly afterwards.
"He looked strong and took his chances. I'm all right about it and I'm pretty much used to it. You just have to roll with it. It is what it is."
O'Sullivan had started in style with two century breaks to establish a 3-1 interval lead, and looked all set to extend his dominant record over his rival, who had not beaten him since the 2016 World Championships.
There had been no sign of O'Sullivan's impending demise when he rifled in a long red in the opening frame which he proceeded to take in emphatic fashion with a break of 128.
But the top seed was unable to punish Hawkins for a missed pink to the middle in the next and a break of 57 proved enough for the Kent man to level the match at one each.
Hawkins missed two early chances in the next as he fell back behind, before O'Sullivan deposited his second century, a 114 which swept him into the interval with an ominous 3-1 advantage.
Hawkins clawed back within a single frame but when he missed an easy red on 17 in the next, it looked like his still-slim chance of causing an all-too-rare upset had disappeared.
Instead, a display of petulance by O'Sullivan, when he smashed his fist onto the table after missing a red to the middle early in the seventh frame, proved the turning point.
A 73 clearance by Hawkins reduced the deficit again, and subsequent breaks of 75 and 88 without reply completed his dramatic turnaround and took him to the verge of victory.
Drawing on all his experience, Hawkins extended his run by building a break of 60 in the next and when O'Sullivan failed to take a chance when his opponent ran out of position, his title defence was all but over.
"It's been eight years since I beat him so it's a massive win for me," said Hawkins. "So many times I've been in this position against him and I've just crumbled, but I didn't crumble today.
"I'm so proud of the way I stood up and took it the way I did. Hopefully it will give me more confidence. If I can't take confidence from a win like that, I don't know what's wrong."
Concluding a dramatic opening session of the Championship, Shaun Murphy edged a 6-5 win over former champion Zhao Xintong, who is on the comeback trail after a two-year ban for his indirect involvement in a match-fixing scandal.
Murphy blazed into a 3-0 lead but was pegged back by the Chinese star, who forced his way through four qualifying rounds and threatened to extend his run before the Sheffield man seized his chance in the decider.
Afterwards Murphy suggested that his recent coaching arrangement with the famously combative former world champion Peter Ebdon might have given him the edge to get over the line.
"Maybe in the last few years I've gone a bit soft," said Murphy. "I think I've probably forgotten over the years that out there, in the pit, it's gladiatorial.
"I've probably gone a bit genteel over the last couple of years, but no more. Working with Peter has changed that."
