Luke Humphries caused the biggest shock of the World Darts Championship, ending the reign of defending champion Rob Cross with a stunning 4-2 victory.
Cross came into the match with an eight-match winning streak at Alexandra Palace after his title on debut last year, but there will be no retention for Voltage as rising star Humphries announced himself on the world stage.
Cool Hand, the lowest ranked player in the last 16, rallied from 2-0 down to take out four consecutive sets, including the final three legs in 36 darts, to secure the biggest win of his fledgling career and a last-eight showdown with Michael Smith.
Smith had things all his own way and he was only the fourth member of the top 16 to reach the last eight with a 4-1 victory over Ryan Searle.
Remarkably, as a perennial figure in the world's top 10, Dave Chisnall has only made the last eight once before - Gary Anderson ended his hopes two years ago and the pair will do battle again on Saturday afternoon after Chisnall whitewashed last year's semi-finalist, Jamie Lewis.
Luke Humphries 4-2 Rob Cross, Fourth Round
Luke Humphries inflicted a first-ever Ally Pally defeat on defending champion Rob Cross to reach the quarter-finals on just his second appearance at the competition.
Humphries, who sits top of the Development Tour Order of Merit and has already beaten Stephen Bunting and Dimitri Van den Bergh, declared himself a potential champion after a 4-2 win showcased all the hallmarks of an emerging star.
Voltage was at his brilliant best to claim the first set with a 104 average and finishes of 107 and 106 serving early notice of his credentials.
With the pair locked at 2-2, and having missed only one dart at double in the match, Cross contrived to miss three for a 2-0 lead, only for Humphries to make a mess himself and allow Cross to forge a 2-0 advantage.
However, rather than shrink, 'Cool Hand' was inspired and claimed a brilliant third set with an average of just over 105 following a three-leg burst that concluded with a superb 115 kill on the bullseye.
Humphries was inspired and made it four legs on the bounce when he landed a 114 finish with the champion handily placed and, when Cross missed two to force a decider, Humphries cleaned up 64 to level the contest.
Humphries' relentless scoring was heaping pressure on Cross and when the champion could not take out 76, Cool Hand pinned double 10 for a 3-2 lead.
Double one bailed out Cross in an edgy opening leg of the sixth set and he swept into a 2-0 lead before Humphries' fireworks took him across the finishing line.
A rapid 11-dart leg from Humphries kept the set alive and a 14-darter levelled it, giving Cool Hand the chance to throw for the match and, having missed one match dart, he eventually pinning the same target for the biggest win of his life.
Michael Smith 4-1 Ryan Searle, Fourth Round
Michael Smith booked his place in the last eight of the World Championship for the only the second time with a blistering display that featured 10 180s and an average just under 100
Bully Boy recovered from a 14-dart break to claim the opening set, three sets on the bounce for the 10th seed, but Searle was not without his chances having seen darts at double go begging in almost every leg.
It was the turn of the world no 61 to start fast in the second, a brilliant 104 finish secured on his way to a 2-0 lead before Smith rallied for another three-leg burst - a spellbinding 130 sealing a 2-0 advantage.
Smith went through the gears, averaging 121 in four minutes, to sweep the third set and stand on the brink of victory. A 15-dart leg got him off to a steady start before back-to-back 11-dart legs left Searle stunned and 3-0 down.
Searle stopped Bully Boy's six-leg run to start a high-class fourth set that went the distance thanks to Smith's brilliant 126 but, having seen Smith miss two darts for the match, Searle pinned double 10 to get a set on the board.
An early break from Searle set him on the way to another 2-0 advantage, but Smith fought back brilliantly, reeling off another three-leg burst and sealing only his second ever place in the last eight at the sport's premier event.
Jamie Lewis 0-4 Dave Chisnall, Fourth Round
Dave Chisnall needed five match darts to beat last year's semi-finalist Jamie Lewis 4-0 and set up a quarter-final showdown with Gary Anderson.
Lewis started fast amid a barrage of big scoring from both men but Chizzy has found a consistency to his game at Ally Pally that has been missing for a while. A classy 76 levelled the set before a brilliant 10-dart break of throw gave him the opening stanza.
Again it was Lewis, known as Fireball, who hit the front in the set, taking the first leg only to be hit by another rapid-fire blow from Chisnall, who raced through the next three legs to move clear with an average of 105, an 11-dart break doing the damage.
Lewis was having to dig deep, a brilliant 118 finish looked to have kickstarted a comeback from 2-0 down in the third set, and he capitalised when Chizzy missed eight for the set to level things up.
But the St Helens thrower kept his cool, Lewis' four missed set darts gave him a window which he barged through to move within a leg of the match, and the 12th seed rattled off three of the last four legs to seal his return to the last eight.
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