Dave Chisnall was knocked out of the PDC World Darts Championship after a 5-1 loss to Luke Humphries.
The number 11 seed from Morecambe struggled to find his groove and missed several chances as Humphries eased into a semi-final clash with Scott Williams.
Humphries started quickly in Monday night's quarter-final, winning the first set 3-1 as Chizzy looked out of sorts. But taking advantage of a reprieve when his opponent missed doubles in the first leg to break the throw, Dave levelled by pinching the second set 3-2 on double 2.
A scrappy third set went to Humphries with a clinching 12 dart leg after Chizzy missed two opportunities at double 12 to break the throw in the previous leg. But Chisnall came roaring back in set four, producing his best darts to that point to quickly go two legs up, before allowing the pre-tournament favourite back in with a wild miss on double top. 'Cool Hand Luke' took full advantage after Dave missed another set dart at tops, picking Chizzy's pocket to go 3-1 up in sets.
Both players improved in set five, peppering the treble 20 as Chisnall upped his three-dart average to more than 113. Both men missed doubles in the fourth leg, Chisnall edging it, but then Humphries snatched the decider with his 11th maximum and a brilliant 121 finish to go 4-1 up.
Dave then missed another double at the start of set six, Humphries duly checked out, won the second leg with another 180, then reached his first world semi-final with a clinical 117.
Chizzy, who has never been beyond the semis at the PDC World Championship, had reached this year's quarter-finals with wins over Cameron Menzies, Gabriel Clemens and Daryl Gurney.
Earlier, unseeded Williams had shocked three times world champion Michael van Gerwen with a 5-3 win.
In the other semi-final, 16-year-old sensation Luke Littler will play Rob Cross, who stormed back from 4-0 down to shock Chris Dobey 5-4.