Ted Hankey pulled off the shock of the round at the BDO World Championships by beating second seed Scott Waites 4-3.
Twice champion Hankey - nicknamed 'the Count' - came from 2-1 and 3-2 down to book his place in the quarter-finals with a 144 checkout.
Number three seed Dean Winstanley threw away a two-set lead in losing 4-3 to fellow Englishman Alan Norris.
Martin Atkins survived a scare against 10th seed Willy van de Wiel to reach the last eight for the first time.
He was leading 3-0 before the Dutchman staged a comeback, but Atkins sealed a 4-2 victory with double top.
In the night's other match, Christian Kist of the Netherlands followed up his shock first-round win against Jan Dekker with an impressive 4-2 triumph over Belgium's Geert de Vos.
Defending champion Martin Adams was among those who reached the quarter-finals on Tuesday.