Ronnie O’Sullivan exited from the Northern Ireland Open as Kyren Wilson held his nerve to earn a 4-3 last-16 win over the five-time world champion.
Wilson, 24, took the opening three frames in Belfast helped by a series of long pots before O’Sullivan levelled by firing three successive centuries.
However, Northamptonshire man Wilson’s 70 break secured a thrilling win.
Welshman Mark Williams ended John Higgins’ winning run as he clinched a 4-1 last-16 win over the in-form Scot.
O’Sullivan, 40, was beaten by Higgins in the final at last week’s Champion of Champions event in Coventry and was hoping for a morale-boosting triumph in Belfast ahead of the UK Championship.
However, last season’s Shanghai Masters champion Wilson produced superb long potting early on to largely shut out O’Sullivan, who did spurn a glorious chance in frame three after his opponent broke down while on a break of 63.
A tremendous opening long red allowed O’Sullivan to respond with a quickfire 108 break in frame four and he punished a missed pink from Wilson with a run of 117 in the next before a contribution of 126 levelled the contest.
At that stage, Wilson had potted only one ball in three frames but he regrouped to close out the match with his nerveless 70 in his first meeting with O’Sullivan.
“You are the underdog against Ronnie, and you are expected to lose by everybody so I was on a win-win really,” said world number 15 Wilson after his win.
“I was just glad I managed to bring the best out of him and that was a bit of a feather in my cap.”
Wilson will face another ex-world champion Williams in the quarter-finals on Friday after the Welshman overcame Higgins.
Higgins went into the Belfast tournament aiming for a third title in as many weeks after his triumphs at the China Championship and Coventry event.
The four-time world champion compiled a maximum 147 in his victory over Sam Craigie on Wednesday but after whitewashing China’s Zhou Yuelong on Thursday afternoon, he was unable to overcome Williams in the evening.
The lengthy match between Wilson and Higgins meant a late start for local star Mark Allen in his last-16 encounter with Gary Wilson.
Barry Hawkins and Michael White both produced match-clinching century breaks to complete respective 4-0 and 4-2 wins over Jack Lisowski and Dominic Dale.