Luke Humphries was furious with himself after losing the second set of his World Grand Prix quarter-final win over Jonny Clayton.

'Cool Hand' was a set up and cruising towards the semis when a slow start to the second left him chasing a two-leg deficit. A comfortable hold of throw halved Clayton's advantage, and Humphries had a dart at tops to make it 2-2.

But a painful miss opened the door for the Welshman, who took out 85 to send Humphries strutting off stage at the break. As he did so, the reigning world champion looked to the section of the crowd where his loved ones were sitting and clearly shouted the words 'threw that away'.

Humphries was on the ropes early in the third as Clayton took another two-leg lead. But a mega 146 checkout from 'Cool Hand' proved to be a major turning point as he harnessed his momentum and came back to win the set, with Clayton missing two darts to a set up.

Moving into the fourth, Humphries could have closed the show quickly, but three missed match darts saw Clayton pull one leg back and then force a decider.

With his World Grand Prix title defence on the line, Humphries took out double 4 to win 3-1 and set up a semi-final against Ryan Joyce, who upset fourth seed Rob Cross earlier in the night.

"That’s probably the most nervous I’ve felt in a long time," Humphries told Sky Sports. "It’s hard playing your friends. It’s not like me, but I think there is an opportunity to win [the title] again and maybe I’m trying too hard.

"Really tough game that one and I just got through it in the end. Usually the deeper [into a tournament] I get, I get better, but I was just trying too hard. I feel really good though, my game is in a good place and I will go into tomorrow in a confident mood. I know I can do it when it matters most. I prefer the longer format so I should be a lot more relaxed tomorrow."

Prior to Humphries' quarter-final victory and Joyce's shock win, Mike De Decker sealed his first major semi-final appearance with a dominant 3-0 win over James Wade. Of the players remaining, Humphries is the clear favourite to retain the title he won 12 months ago.