Riyadh Season World Masters: Mark Allen takes out Mark Selby with incredible comeback win

Allen took the decider by doubling the black as he came back from 3-1 down, with Selby appearing to cruise through the opening frames.

With a two-frame cushion, Selby had taken a 54-point lead in the fifth, but a miss allowed Allen to step up with a clearance of 65. And it was a similar story in the sixth as a missed black allowed Allen to come from behind to level it.

A tense deciding frame was full of mistakes and fouls as Allen again came from behind, helped by a fluke green before his stunning winning shot.

“I actually thought the white was going to drop in,” he said on Eurosport. “It was such an easy shot to flick off the black, but I thought, ‘No, I’m going for it’. As long as I got a really good white, I’d be alright.”

Ali Carter cut a frustrated figure after losing his quarter-final 4-1 to world champion Luca Brecel.

Carter had looked on course to level the match at 2-2 but his night unravelled after a late missed brown which he blamed on a scoreboard mistake.

“I’m clearing up, I want to get on with it and the scorer’s got the score wrong,” he said. “I’ve stunned up the table, thinking I can play anything I want.

“I look at the scoreboard and now all of a sudden I’m thinking, ‘Have I miscalculated?’ and it’s just completely put me out of my rhythm.

“I thought I’ve got to pot the brown to be able to draw. I don’t know how it worked out but I’m looking at the blue and all of a sudden the ref said I’m on 41 and I’m 22 behind or something. It just completely threw me.”

Carter was also unhappy with the four-hour wait for his match to start after Selby and Allen went long.

Judd Trump came from behind to beat an unlucky Shaun Murphy 4-3. Murphy had opened up with breaks of 126 and 105 to storm into a 2-0 lead but Trump came through a tricky third frame before levelling it with a break of 75 in the fourth.

Murphy nosed back in front and appeared to be heading for the final four as he took a big lead in the sixth frame, only to clip a red and allow Trump a way back in – one that he duly took with break of 69 before he bossed the final frame.

Trump will play Ronnie O’Sullivan in the semi-finals after the world number one beat John Higgins 4-0.

O’Sullivan made three century breaks in the opening three frames in the whitewash victory, while Higgins failed to pot a single red in the game.