Aslan Karatsev would not have figured as a final four lock when pundits cast their eyes over the Australian Open men’s draw two weeks ago.

But the boisterous Russian has written another chapter in this unlikeliest of fairytales, downing a limping Grigor Dimitrov to book his place in the Australian Open semi-finals with a 2-6 6-4 6-1 6-2 victory.

Karatsev, who never played a grand slam main draw until this fortnight, is now the first man in the Open era to make the semi-finals on his debut – something six other debutants in quarter-finals could never manage.

“Yeah, I got around 200, something like this, messages on WhatsApp. Yeah, I think it’s going to be more,” the Russian qualifier said moments after his crowning glory.

Entering the tournament, the 27-year-old Karatsev had earned $794,900 in his whole career. After this showing, he’ll receive a minimum $850,000 pay cheque (before taxes).

In a cruel, ironic twist, changes to the Open’s prize money for a pandemic-afflicted year to reward early-round losers means he’s been dudded an additional $190,000.

You win some, you lose some.

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Karatsev also guaranteed he would be a top-50 player and can rise into the top 15 if he manages the unthinkable – hoisting the Norman Brookes Challenge Cup on Sunday.

A far cry from his pre-tournament ranking, outside the top 100.

Karatsev started out the match seemingly as if the occasion – the empty expanse of Rod Laver Arena, his maiden major quarter-final, a mature opponent on the other side of the net – were overwhelming.

His laser-fast groundstrokes were struggling to find their range, and the lines. His early break was scuppered by 19 unforced errors as Dimitrov spun the match around with five unanswered games.

However, the Bulgarian 18th seed would rue not capitalising on an early advantage in the second set, letting slip five chances to break in Karatsev’s six-deuce opening service game.

Having endured one round of Russian roulette, Karatsev faced another in his next service game after Dimitrov nailed a backhand drop shot. But three aces in a row snuffed out two more break chances.

And that’s where the script, a regulation straight-sets affair, was flipped.

Karatsev immediately broke the Bulgarian as his whipped forehands went limp, and another break at 5-4 elicited a cry of “Come on!”

Then, the Russian survived his most crucial gut check – and arguably, the match – as Dimitrov’s reliable, Federeresque backhand went completely awol to level the set score.

Aslan Karatsev has blown his opponents aside to become the first men’s grand slam debutant to make the semi-finals. Photo: Getty

Dimitrov started the third set with nerves riddling his first service game. And then two drop shots, both unrewarded, hinted at something more sinister as the Bulgarian condensed points.

Karatsev broke again, bending his hapless opponent backwards.

However, after pulling up lame late in the third and struggling to launch into his serve – at times, he was simply rolling them over – the Bulgarian showed it was an agonising battle against injury, rather than tiredness.

Making matters worse, he could barely track down the ruthless firepower emanating from the Russian’s racquet as he whacked ridiculous returns on the stretch. At times, he would simply walk away from returns, not opting to be played into rallies where he was pummelled backwards.

A clearly-hampered Dimitrov then trudged to the benches in submission before Karatsev returned another meek serve on set point to hand his opponent a two sets to one lead.

“I was trying to play with him to see – to go less with unforced [errors]. Yeah, I took his break, I closed the set, and then in the third set I think I felt already the – I think it was the back,” Karatsev would later say.

The Bulgarian confided in the tournament physiotherapists he suffered a pelvic injury during practice, which seized up his lower back.

Dimitrov’s back proved his major undoing after running out to a one-set lead. Photo: Getty

After an extended off-court injury timeout – and perhaps an ibuprofen and a good rub down – Dimitrov rollicked out of the gates in his opening service game. An electric backhand down the line after a 23-shot rally during his second showed flashes of his world-beating form.

Every game thereafter, Dimitrov looked primed to pull the pin. But no. He pushed through pain. It was, admittedly, more painful to watch.

Karatsev appeared unfazed by the disruption, however, and converted a vital seventh break of the match to take the advantage – one he wouldn’t cede as the quarter-final reached its anticlimactic conclusion.

“I’m sorry guys, I’m sorry,” Dimitrov wailed to his player’s box. A trudge to the towel before a Russian forehand return, and his fate was sealed.

One final regulation backhand later and Karatsev stood, dumbfounded, as his stay at the Australian Open was prolonged by at least two more days.

“I try to believe every match what I’m doing on the court, and it’s helped me to win matches,” Karatsev said.

With an is-he-injured-or-is-he-not Djokovic or Alex Zverev – not without his controversies amid domestic abuse allegations from an ex-girlfriend – waiting in the wings, that belief may produce one final plot twist.