Martin Adams battled back to record a momentous 4-3 win over Martin Atkins in the Lakeside World Championship.
Atkins hit eight maximums as he stormed 3-0 ahead but in the deciding leg of set five the Leeds man missed the double top he needed to seal victory.
After that Atkins crumbled and it was Adams who won seven consecutive legs to turn the match on its head.
Defending champion Raymond van Barneveld kept up his hunt for a fifth title, beating Scot Gary Anderson 4-1.
Adams finished as runner-up to the Dutchman last year and was relieved to reach the quarter-finals.
"That was tremendous - it has to rate as my best ever fightback, no doubt about it," said the second seed.
"Years ago panic would have set in, but you've got to keep your head on and I never say die."
In contrast, Atkins blamed his inexperience for relinquishing a winning position in his third match at Frimley Green.
"I had it won and let it get away," said Atkins.
"On the match dart at double top I thought about it as I was throwing and after that it was all Martin.
"It's only my second time in the tournament and I think experience told in the end."
Van Barneveld and Anderson both showed better form than in the first round - Anderson even hit a 180 on his first throw.
The Scot checked out on a double 13 to level the match at 1-1 but from then on Van Barneveld took control.
"I played much better than in my first match," Van Barneveld said. "I didn't miss anywhere near as many doubles."
The world number three goes on to meet Tony O'Shea after he beat Vincent van der Voort 4-0.
And Mike Veitch beat qualifier Steve Roberts 4-3 to set up a game against Adams.