Tournament favourite Michael Van Gerwen overcame a mid-match wobble to beat Ryan Joyce 5-1 and make it into the last four.
Van Gerwen's path into the semi-final looked a formality as he took the first set 3-0 and averaged 109.98.
But the Dutchman went off the boil and Joyce was close to levelling the match at 2-2 before an 11-dart leg from Van Gerwen restored his control.
The number one seed will meet old foe Gary Anderson in Sunday's semi-final as he attempts to win a third PDC world title.
Earlier in the evening session, Michael Smith booked his own last-four date against Nathan Aspinall with a 5-1 victory over Luke Humphries.
Smith dominated after taking the first set against the darts, and Humphries never looked like repeating Friday's quarter-final victory over reigning world champion Rob Cross.
The 28-year-old from St Helens averaged nearly 103 as he reached his first PDC World Darts Championship semi-final.
