Tony O'Shea ended Martin Adams' hopes of a third successive world championship title with a 5-2 quarter-final win at the Lakeside.
The number eight seed, a runner-up in 2009, will now meet Dutchman Wesley Harms in the semi-finals.
Harms, the 13th seed on his Lakeside debut, beat Paul Jennings 5-2 to reach the last four.
In the women's tournament, England's Deta Hedman will play Russian Anastasia Dobromyslova in Friday's final.
Hedman beat Lorraine Farlam 2-1 in the semi-finals, while Dobromyslova triumphed 2-0 over nine-time champion Trina Gulliver, who has failed to reach the final for the first time.
O'Shea's victory over world number one Adams leaves the man from Stockport as the highest seed left in the tournament.
"I knew the pressure Martin was under," said O'Shea. "To play well and beat him has made my year.
"I've played better than that, but if I can play that well in front of this crowd, then there's nothing I can't do."
In Friday's quarter-finals Alan Norris meets Christian Kist and Ted Hankey takes on Martin Atkins.