Trailing 2-6 overnight, Allen produced a superb response. A scrappy opening frame set the tone, with both players missing chances before Allen capitalised on a foul to reduce the deficit. He then edged a tense, hour-long battle that required snookers, before accelerating sharply in the following frame.
Allen ignites comeback
At his fluent best, Allen compiled a superb 145 total clearance, the highest break of this year’s tournament, to close the gap. With Wu’s composure faltering, the Antrim native pressed home his advantage, levelling at 6-6 and then moving ahead for the first time with a clinical 121 clearance.
What had threatened to become a one-sided turnaround, however, took a surreal turn in the next frame.
Record frame halts momentum
A missed black left awkwardly over the corner pocket, turning the table into a tactical stalemate, with both players reluctant to disturb a cluster of reds.
What followed was an extraordinary passage of play, with safety exchanges stretching on and the referee eventually warning of a possible re-rack.
Allen, leading but unable to progress, took the unusual decision to pot the black deliberately in an attempt to force movement. It backfired. Wu pieced together enough scoring chances to regain control and, after a drawn-out tactical battle, secured the frame on the pink after 100 minutes -- the longest in Crucible history.
"In a nutshell, that frame is an embarrassment to snooker. The referees and players’ association need to ensure it never happens again," said six-time world champion Steve Davis.
The bizarre conclusion halted Allen’s surge but could not stop it entirely. After a session of extremes, from free-flowing centuries to near-standstill stalemate, the match stands perfectly poised at 7-7.