Kyle Edmund can never have endured a longer 20 seconds. When Grigor Dimitrov challenged the “out” call on his final slice backhand, Edmund looked up at the big screen and covered his mouth with his palm.

Yet the Hawk-Eye ruling, like the result itself, was categorical. The ball was long, by a couple of inches. Dimitrov, the No. 3 seed and recent ATP Finals champion, was out of the Australian Open. And Great Britain had a new sporting hero.

On Thursday, Edmund will play Marin Cilic for a place in the Melbourne final, after Rafael Nadal made a dramatic exit from the tournament last night. This was a heartbreaking moment for Nadal’s millions of fans, yet it can only have improved Edmund’s chances of becoming the most unexpected slam finalist since Martin Verkerk at the 2003 French Open.

Hold on a minute, though. We are getting ahead of ourselves. Simply to reach the semi-finals is an incredible feat. Andy Murray, with no fewer than 21 appearances at this stage of majors, might have made it look easy. But many fine players have never gone so far, from Nick Kyrgios to David Goffin. And then there is Edmunds unprepossessing ranking (49) to consider. Until Tuesday, no unseeded man had reached a major semi-final since Rainer Schuettler and Marin Safin, both at Wimbledon in 2008.

A few wise old birds did see this coming – even if your correspondent was sadly not among them. The tennis seismograph picked up advance tremors three weeks ago, when Edmund beat Hyeon Chung in the second round of Brisbane. Now that Chung has ejected Novak Djokovic from Melbourne Park, that win looks like the proverbial canary in the coalmine.