Rehan Ahmed, putting the game in super fast forward

The day had been drifting in Karachi. Certainly by Ben Stokes' usual twist-over-stick approach in the field. 

Within nine overs of day three of the third Test, Jack Leach had taken the first three wickets in Pakistan's second innings, all across the space of six deliveries of left-arm spin, for no runs whatsoever. The hosts were in front, though only by four. 

That would swell to 49 by lunch, and onto 104 by the 50th over. By then, Babar Azam and Saud Shakeel, 45 and 47, respectively, had brought up a century stand between them. Leach had already completed a bumper 16-over spell from the University Road End, as Mark Wood and Ollie Robinson tagged in and out at the Pavilion End. Stokes, irked, had indulged in one of his self-flagellation spells of eight overs on the bounce with little of note beyond a couple of plays and misses. As we ticked close to three hours of this stand with no jeopardy barring the odd bit of reverse-swing that wasn't causing right or left-hander any real trouble, the question got louder. Where was he? 

You'll know who "he" is if you've been following this Test. You'll definitely know who "he" is if your browsing has brought you to this page. Rehan Ahmed's Test career is just three days old and English cricket is already infatuated with the teenage legspinner off the back of his first two Test wickets, sumptuous googlies, swaggering shoulders and a beaming smile to make even the floodlights of the National Stadium redundant. 

All of the above are reasons for both excitement and caution. Leggies, by their nature, are unknown quantities at the start of their journeys, in part because the craft they need to tame is intoxicatingly wild. But in his fourth appearance in first-class cricket, in which he became the youngest debuting Englishman for the Test team - and thus the youngest wicket-taker for the side - there was already a sense he possessed the explosives to blow this match wide open. Finally, in the 51st over, Stokes handed Rehan the ball. The rest, as on day one, was historical. 

Just 24 overs later, Rehan, at 18 years and 128 days, had become the youngest debutant in men's Test history to take a five-wicket haul. Pakistan had been skittled for 216, giving England a target of 167 for a series sweep which now sees them need just 55 when they resume on day four, with eight wickets in hand having only had 17 overs before the light took them to stumps on Monday. 

Rehan was one of those two batters to fall, introduced upon the dismissal of Zak Crawley, as the first open sighting of the Nighthawk role that Stuart Broad was given during the summer but was never able to showcase. While Broad sat in the Sky studio, the understudy came out on the opening night. 

"Just 'try and finish it tonight'," was the instruction, Rehan revealed. "I think we would have as well if we had the last seven overs of the day." He skipped down and hit his first ball back over Abrar Ahmed's head for four. Was that the instruction from head coach Brendon McCullum, to strike a telling blow first up? "I said it to myself, if anything," Rehan replied. He managed one more boundary - panned through cover - before being bowled by Abrar attempting a swish across the line. 

Those who know Rehan speak of a cricketer whose default is to put the game in fast-forward, and already the career seems to be tracing at that speed. Nevertheless, patience was evident here, not least with the three-hour warm-up having bowled just two overs the night before. 

He began calmly, unperturbed by the fact he was up against a set Babar and Shakeel, generational great and impressive newbie, right and left-hander, with an old ball and a not-all-that responsive pitch for company. And then, with one of the worst balls he has bowled, he broke them up. 

That he described the first wicket of the five as "God-sent" said it all. Even an atheist might have doubted their beliefs when Babar smacked a long hop straight to Ollie Pope at midwicket. A wicket is a wicket, as Rehan was keen to stress. The joy, both his and that of his team-mates, was proof of that. 

Three overs later, Mohammed Rizwan joined Babar in Rehan's pocket. A smart legbreak drew the wicketkeeper-batter forward before dipping shorter than he had anticipated and pitching wider than he had calculated. Ben Foakes took the edge with minimal fuss. 

"I liked Rizwan's wicket," Rehan explained, "because I've been working on my legspin quite hard for the last two months with Jeetan [Patel, England's spin-bowling coach]. So to get one to spin a little bit the other side, it was great."

When it all first began, after a brief dalliance trying to emulate his father, Naeem, as a quick bowler, Rehan found himself only being able to bowl wrong-uns rather than the stock leggie. And even if we are still closer to the start, when your googly is further along, why not have the orthodox delivery as the change-up. 

You could argue Shakeel was not totally sure which was on its way to him when he decided to sweep around the corner. A bit of extra bounce brought about a top-edge to Leach at square leg. Just like that, a trio of accomplished batters were chiselled out in the space of 17 balls from Rehan. Not since Home Alone has a kid taken out seasoned pros with such aplomb around Christmas. 

With the tail now exposed, the only thing in the way of a prospective five-wicket haul was the feasting of his team-mates. Joe Root snared Faheem Ashraf just after tea, before Rehan's fourth came via a botched heave down the ground from Mohammad Wasim. The fifth was no bunny, though: Agha Salman the next to be done by bounce on a flat-bat shot, caught by Harry Brook at short leg. 

Just like that, Saturday's honour of being the happiest day of his life was bumped to second by Monday. "I still don't think it's sunk in yet," he said in his press conference. No doubt by the time it does, he'll have already begun thinking of the next one.

Upon confirming figures of 5 for 48, Rehan performed a quick sajdah - bowing to God - before hopping back up for another round of hugs from team-mates and then leading them off. He flung the ball in air between showing it to all corners of the ground, then waving and fist-pumping to his father and brother, Raheem, sat perched above the sight screen who returned the gesture ten-fold. 

He was back out as quickly as he walked off for his Nighthawk duties, and didn't hang around out in the middle. A second brisk exit came, this one much angrier at failing to connect for a third four, before he was bouncing into media duties and then out of our lives again. At least until the next time.

Thanks to Rehan, England went into the dressing at the innings break with typically cavalier ambitions of possibly getting home in the early hours of Tuesday morning. Alas, they'll have to stick around in Karachi and knock these remaining runs off for what has been a breakneck 3-0 series win before eyeing up any potential flights on Tuesday evening. 

As for the 18-year-old, day four of his first Test will be the neat culmination of a year that began with him as an unknown quantity in the England Under-19 World Cup squad. Now, everyone knows his name. 

They say it's important to give kids time to work things out at their own pace. But Rehan seems to have a lot of it sussed already. He is by no means the finished article yet is already offering so much. Even in such a high-pressure environment, he has emerged as a key difference-maker for an England team full of them.