Unseeded Gary Robson won the final three sets to beat 2001 champion John Walton 4-3 and reach the last eight at the Lakeside World Championship.
John 'Boy' Walton threw for the match at one stage against Robson
The 39-year-old Robson, who beat wonderkid Michael van Gerwen in round one, fought back from 3-1 down to win.
Robson will next play Dutchman Niels de Ruiter, who beat sixth seed Simon Whitlock of Australia 4-3.
Paul Hanvidge beat Albertino Essers 4-1 and goes on to meet Phil Nixon, who upset 10th seed Martin Atkins 4-1.
Scotland's Hanvidge reached the quarter-finals for the second consecutive year, finding his range after dropping the opening set.
Nixon, making his debut in the tournament at the age of 50, showed his opening win over Darryl Fitton was no fluke by accounting for 10th seed Atkins in a match notable for the number of missed doubles by both players.
Walton, from South Yorkshire, threw for the match but could find no answer as Robson hit form.
He clawed his way back to 3-3 and after requesting a comfort break, took a vital first leg of the decider against the throw as the world number 14's game became increasingly ragged.
"I think John 'Boy' stepped off the gas a touch because he was invincible for two sets," said the 39-year-old Robson.
"But I never gave in. He gave me some chances and I took them.
"I needed the loo when I was 3-1 down. But I thought I wouldn't ask at that point because I thought he would bosh me 4-1!
"I didn't see any way I could break his throw in the next set, so I thought I would wait.
"I won the set and then waited again, but as soon as it got to 3-3, I had to go."