Defending champion Martin Adams' hopes of a record-equalling third consecutive BDO World Championship title were shattered after the top seed was dumped out in the quarter-finals by Tony O'Shea at Frimley Green.
The Stockport eighth seed triumphed 5-2 and also claimed a tournament-high 170 checkout in the fourth set, after Adams had put himself in line for the £3,000 out-shot prize with a 161 in the third.
O'Shea blazed into a two-set lead but was pegged back by Adams and needed his big checkout to help end the champion's revival and move 3-1 in front in their best-of-nine match-up.
Adams responded by easing through the fifth set but O'Shea kept his nerve to take the next on double 16 and the underdog completed his victory by winning the seventh set unchallenged on a 52 checkout.
O'Shea will play Wesley Harms in the semi-finals after the Dutch debutant continued his dream run in the tournament by holding off the determined Paul Jennings to clinch a 5-3 win.