Mark Allen and Wu Yize all square after record 100-minute frame at Crucible

Steve Davis, a six-times world champion, told BBC Sport: “In a nutshell, that frame is an embarrassment to snooker, and the referees and players’ association need to try to work out a way that never happens again.”

Earlier, Shaun Murphy battled back to leave his semi-final against John Higgins finely poised at 8-8 ahead of their evening session in Sheffield.

The standard of play was a sizeable upgrade on Thursday’s scrappy first session that was shared 4-4. But both players still wasted big opportunities to open up a commanding lead in their best-of-33 battle.

Four-time world champion Higgins looked as if he might be capable of achieving that advantage after taking an 8-6 lead and putting Murphy’s cueing under pressure. But Murphy, the 2005 champion, held his nerve to draw level and restore parity in a session where he had made only one break over 50.

Murphy was in pole position to win the opening frame before his run of 49 ended by missing a straightforward black when attempting to cannon a red and keep position.

Higgins made a 72 clearance to lead for the first time, but Murphy kept his focus in the next frame with a fine response of 88. A brilliant long red would get Higgins going again and he had reached 67 before striking a frame-winning black too hard. The Scot was back in front though as a Murphy miscue let him finish matters off.

John Higgins is aiming to reach his ninth Crucible final at the age of 50. Photograph: Mike Egerton/PA

Murphy tied the scores at 6-6 after a break of 47 put him in command. Higgins failed to cut a difficult black into the corner and Murphy capitalised to reach the mid-session interlude with a spring in his step. That bounce quickly disappeared as Higgins made a decisive 57 break and a freak screw back in to baulk in the next frame saw Murphy lose position and momentum.

Higgins punished him with a break of 86 – his best of the match – before Murphy edged a nervy 15th frame which lasted 37 minutes. Murphy was 53 ahead with 51 remaining and Higgins needing one snooker, which he got when the Englishman found himself tucked behind the black and slid past a red up the table.

There were more safety exchanges with various colours tied up and Murphy, having potted a wonderful long green to leave Higgins requiring another snooker, could not breathe easily until sinking the pink.

Murphy was vulnerable in the final frame after a missed pink into the middle pocket ended his flow at 28. But Higgins missed a red with the rest and a double kiss cost him dear as Murphy made a 31 clearance to leave the contest on a knife edge.