Provisional world number one Ken Doherty became the highest-ranked player to bow out of this year's Maplin UK Championship when he lost 9-6 to Joe Perry in York.
The Irishman, who before this tournament had been on course to move up from his current number two position, won only one of the last seven frames against a man who is a specialist in this event.
Perry has reached the semi-finals for the last two years and is now into the last eight, in which he will meet John Higgins.
Resuming with a 5-3 overnight advantage, Doherty made the only three century breaks of the match but otherwise struggled to score heavily as Perry gradually got on top.
'Joe shut me out for three frames,' said the 1997 world champion. 'He played really well tonight, and I missed a few chances. I should have gone 6-3 up - and if I had it would have been different.
'Things just weren't happening for me. But sometimes that's the way it goes, and it makes things pretty difficult.'
Ding Junhui stayed on course to emulate Stephen Hendry and Steve Davis by becoming only the third man to successfully defend the title.
The Chinese teenager, who captured the sport's second most prestigious crown as a qualifier last year, won 9-5 against Matthew Stevens to reach the quarter-finals.
It was a typical Ding display. He produced some brilliant long pots and compiled breaks of 111, 100, 92 and 81 but also played shots where a lack of concentration was evident.
That can be forgiven, however, the 19-year-old having won three gold medals at the Asian Games in Qatar immediately before this event - and he admitted his busy schedule is taking its toll.
'I'm relieved to have won, because I didn't play very well,' Ding, who will next meet Peter Ebdon, said through an interpreter.
'Near the end of the last frame, I played a blue a bit too fast and I regret that a bit. It felt quite hot in the arena, and that disturbed me.
'I'm not feeling very stable just now. I didn't feel very confident before the match and I was a bit worried in the first session, because Matthew played well.'
