Terry Griffiths led Steve Davis after winning the first four frames of the match, but finished the first session at 4–4. Davis won six of the eight frames in the second session to lead 10–6. In the first frame of the third session, Griffiths committed a by touching a ball with his waistcoat, following which Davis made a break of 80 to win the frame. Davis also took the next two frames, winning 13–6 to reach his fourth World Championship semi-final. John Parrott also won the first four frames of his semi-final against Ray Reardon, and led 5–3 after the first session. Parrott extended his lead to 9–5 in the second session, but missed two in successive frames to lead by only 9–7 after the session. Reardon won the first five frames of the third session (seven in a row) to lead 12–9, and Parrott won the next three frames to force a deciding frame. With one red left on the table, Parrott led by seven points; Reardon Parrott, and won a to win the match with a break of 31. Due to slow play, only six of the eight frames of the opening session between Dennis Taylor and Cliff Thorburn were played. Taylor took a lead of 4–0, before ending the session at 4–2. The session was described as interesting by Clive Everton of "The Guardian", however, due to the "high quality of the tactical play." The second session was also long-winded, with the match adjourned at 1:21a.m. (after nine hours and 45 minutes of play); Taylor led 10–5, with a frame still to be played. Resuming the match, Taylor won three straight frames to win 13–5 and reach his fifth semi-final. Thorburn said after the match that both players were at fault for the slow play: "I wasn't the only one playing safe. If I had played well, this would have been the longest match ever." There was only one break of over 50 in the entire match, made by Taylor in the final frame. Second seed Tony Knowles played Jimmy White, and led 5–3 after the first session. Knowles made a break of 137 during the session, but missed the black; it would have been the tournament's highest break. He retained his lead through the second session, despite twice being a pot away from being tied; the session finished 9–7. Returning to the match, Knowles won the next two frames but White won a re-spotted black in frame 19.