World number one Paul Foster beat Billy Jackson to set up a quarter-final meeting with Robert Weale at the Scottish International Open.
Scot Foster's first set with Jackson was tied but he won the second 9-3 while Welshman Weale claimed a two-set victory over Les Gillett, 9-6 9-8.
Defending champion Mervyn King overcame Stewart Anderson 13-3 10-5 and Greg Harlow beat Brett Arkley 8-6 3-8 2-0.
Third-seed Harlow will face David Gourlay in the last eight.
Qualifier Robert Paxton, who beat fourth-seed Darren Burnett on Tuesday, faces Simon Skelton in Thursday's opening match in Perth.
Weale then takes on Foster before King plays Ian Bond.
Harlow against Gourlay is the final tie scheduled.
"I've always had to work hard against Billy," said Foster after his victory.
"Every single match we've ever played has always had a tied set or a tie-break.
"I'm pleased with the way I played."
Thursday 10 November quarter-final schedule:
(6) Simon Skelton (Eng) v (Q) Robert Paxton (Wal)
(11) Robert Weale (Wal) v (2) Paul Foster (Sco)
(1) Mervyn King (Eng) v Ian Bond (Eng)
(3) Greg Harlow (Eng) v (8) David Gourlay (Sco)
Friday 11 November semi-final schedule:
King or Bond v Skelton or Paxton
Harlow or Gourlay v Weale or Foster
Coverage from Dewars Centre in Perth continues on BBC Two, the red button and on the BBC Sport website at the following times:
Thursday 10 November 1300-1715
Friday 11 November 1300-1715
Saturday 12 November 1405-1620