Mark Allen produced a moment of magic that left former World Snooker champion John Parrott purring in the commentary box in his mammoth semi-final clash against Wu Yize. The pair produced the longest frame in World Championship history with a one-hour and 40-minute effort.

For a long stretch, it was not an entertaining frame for the Crucible audience, who grew frustrated as Allen and Yize went back and forth with a number of red balls crowded around a corner pocket, but blocked from it by the black. Steve Davis was left disgusted by the deadlock.

He said: "In a nutshell, that frame's an embarrassment to snooker, and the referees' and the players' association need to try and work out a way that never happens again."

But the fourteenth frame did provide some excitement and possibly the best shot of the tournament so far. With Allen requiring snookers to win the frame, down by 16 points with just the pink and black remaining, he produced a stunning play.

With the cue ball and pink in the top right corner, Allen sent the white around the table to slot the white into a narrow gap between the black ball and the cushion at the opposite end of the table.

And BBC stalwart Parrott loved what he was seeing, growing more excited as he followed the cue ball around the table. "What a line this is, what a line this is," he said.

"Oh, this is unbelievable, unbelievable, what a shot Mark Allen has produced there. Wow. That has got to be the shot of the championship."

Unfortunately for Allen, Yize was able to find a way out and ultimately claimed the frame to level the scores at 7-7. The titanic battle continued on Saturday as the pair went back and forth, leaving the scores tied at 11 in the best-of-33 semi-final clash.

Seven-time world champion Stephen Hendry was full of praise for the quality that Allen and Yize produced, with just one session remaining before one qualifies for the final on Sunday.

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"It's brilliant," Hendry said. "As soon as a player gets in, you think the frame's over. Especially with Wu Yize, because the breaks he's knocking in are phenomenal.

"You expect the players to peak at this part of the tournament. Getting through the early rounds is important but nobody really plays their best in the early rounds.

"The longer you're in this, you've got more sessions to settle in and for players to find their very best form. It's who blinks first or last wins or loses, and that's what you want to watch."