Luke Humphries staged a stunning comeback at the PDC World Darts Championship to beat reigning champion Rob Cross.
Cross looked on course to continue the defence of the crown he won during his maiden appearance at Alexandra Palace last year when he surged into a 2-0 lead.
But Humphries battled back to cause an upset by recording a 4-2 victory.
Humphries, who will face Smith in the quarter-finals, said: "If you want to be world champion you don't give up.
That showed a lot about my game and a lot of character to knock out a person who has never lost on that stage.
"It's all about the fightback and if you want to be world champion you have got to do that. I am hugely proud of myself for coming back and for the way I played in those last four sets.
"People don't think I can win this but I say I can, I take a lot of inspiration from Rob."
Cross said: "I'm obviously disappointed. I felt a bit fatigued, to be honest. At 2-0 up I came back out and I didn't feel anything, but fair play to Luke he played great.
"I don't think my scoring was great all the way through, the 100-plus finishes were keeping me in the game and without those I would have lost 4-0. This is going to hurt and I will bounce back next year. That's the monkey off my back now.
"This year has been tough and probably the hardest learning curve I have ever had in my life. I will go and enjoy a normal life now away from darts and if I can do that then I will be fine next year."