Instead it was Williams, 47, who got there – the oldest player to do so since 52-year-old Ray Reardon lost to Steve Davis in 1985.

“I was nervous, because I was so close to my first Crucible one-table match,” Yan told the World Snooker Tour website. “At 11-10 I had a chance to make it 12-10, but I was thinking too much and lost the cue ball.

“[In the first session] I lost my concentration and went 6-2 behind, then brought it back to 8-8 in the evening session. I believe in myself, I can do anything.”

Williams, who was joined in the last four by his “Class of ’92” comrades John Higgins and Ronnie O’Sullivan, said: “This is where the tournament becomes the best venue in the world, for me. I have always said that the one-table set-up is something everyone must try to play once in their career.

“I am just so happy to get to the semi-finals. I am here 30 years on after turning pro and still trying my best.”

Higgins, too, had to come from behind to clinch an epic encounter 13-12, in his case ending the interest of a new, improved Jack Lisowski.

Seeking a warrior-like quality to balance his artistry, the mercurial Lisowski had requested the telephone number of the famously intense Peter Ebdon and enlisted the former world champion as a mentor.

It showed, as he refused to be shaken off by the front-running Scot and overtook him at 12-11 – the first time he had led since frame one. Higgins replied with nerveless brilliance, though, breaks of 105 and 72 sending him through.

There was no such toiling as O’Sullivan progressed to play Higgins, coasting home 13-5 against Stephen Maguire.

Completing a heavyweight semi-final line-up was Judd Trump, who after an underwhelming start to the championship began to suggest he could peak when it counts. He beat Stuart Bingham 13-8.