Mark Williams turned in one of his poorest performances of the season in Dublin to give Paul Hunter an almost unopposed passage into the semi-finals of the €635,000 Citywest Irish Masters.
The provisional world number one slumped to a 6-1 defeat and missed out on the last four of a major event for the first time in six tournaments.
Not since the LG Cup at Preston last October has the Welsh left-hander bowed out before the penultimate round.
But he seemed strangely out of sorts against his Leeds-based rival, who won for only the second time in 12 matches.
Hunter also dashed hopes of a semi-final between best of enemies Williams and Ronnie O'Sullivan.
Williams totalled just 46 points in the six frames he lost as Hunter booked a semi-final on Saturday against O'Sullivan or Matthew Stevens.
"I knew if I played as badly as I had done in my opening two games I would be in trouble," explained the UK and B&H Masters champion.
"But I didn't expect to play badly again. I thought the prospect of meeting Paul would help me raise my game. But he deserved to win and it was always going to happen sooner or later.
"I said earlier in the week I've stopped him winning a few tournaments this season. So I hope now he goes on to lift the trophy because me and him have been two of the most consistent players this season.
"I've had a good run this season so I can't complain," added Williams, whose only success came in frame four with a contribution of 83.