It says a great deal about Real Madrid's injury-plagued season that the Spanish and European champions' likelihood of staying in their favourite competition might hinge upon Raúl Asencio, an inexperienced centre-half who's making only his third Champions League start and who now needs to contain the goal scorer that is Erling Haaland.
Whether Asencio is able to enjoy his 22nd birthday on Thursday will largely revolve around how he copes with a player who is six inches taller than him, 16 kilos heavier and who has scored 47 goals in 47 Champions League matches, in Manchester on Tuesday.
It should -- even in this quixotic, idiosyncratic and unpredictable sport which we love so much -- be a complete no contest.
If, by Wednesday morning, the back pages are full of Haaland's face grinning about the hat trick he's scored, and the damage he's done to Madrid, then nobody would be sufficiently shocked to be put off their breakfast.
But even though this looks like a mismatch, based on the old boxing adage that "a good big one will always beat a good little one," there are some hints that Manchester City's exceptional and ruthless Norwegian might actually have a battle on his hands.
Asencio turns out to be an absolute warrior, and the evidence during his short time in the Madrid first team tells us three very clear facts:
1) He's extraordinarily quick in his sprints to the tackle.
2) He's equipped with fearless, competitive winner's mentality.
3) Madrid coach Carlo Ancelotti is guilty of not having handled, or even understood, the defender's progression very well.
In case you haven't been following closely, I'll give you the backstory which leads us towards the first leg of Real Madrid's knockout tie against Manchester City at Pep Guardiola's HQ.
Asencio is only in the first team because of a plague of injuries among Madrid's central defenders. In fact, as recently as the club's summer tour in the United States, this kid could easily have assessed himself as having been Ancelotti's ninth-choice centre-back. (Behind Antonio Rüdiger, Éder Militão, Jesús Vallejo, David Alaba, Dani Carvajal, Aurélien Tchouaméni, Joan Martínez and Jacobo Ramón). That now looks absolutely ludicrous.
Asencio made his first-team debut only three months ago, against Osasuna, when Militão felt his knee ligaments giving way for the second time in two seasons. The youth academy product came on after 30 minutes, helped Los Blancos keep a clean sheet and gave a beautiful assist to Jude Bellingham, but Ancelotti then dropped him immediately and there was competition for places again. In fact, Madrid's Italian coach kept on preferring the accident-prone Tchouaméni, a converted midfielder, at centre-half instead of Asencio.
It was bewildering then, but even more remarkable now that it's clear that this Canary Island-born warrior is tailor-made for the ultra-demanding life which faces any Real Madrid centre-half.
"I'm a defender who likes to defend," Asensio pointed out after that Osasuna debut. "I play for my teammates ... I like to help them out, and the team comes first for me all the time."
Perhaps that all sounds a bit obvious, but in these days when central defenders are fully expected to be playmakers and full-backs are asked to be auxiliary wingers, fans (and goalkeepers) absolutely love a defender who lives to win tackles, to subjugate rivals and to keep clean sheets.
Santi Cañizares was on Madrid's books for eight years, won a huge haul of trophies with them, Valencia and Spain's youth setup -- and the former goalkeeper is a long-declared fan of this 21-year-old upon whom Tuesday's spotlight will fall.
"Asencio's a player I like very much. I've seen him often because he plays in the same Real Madrid junior team as my son Lucas," Cañizares told national radio. "He looks like a terrific footballer, he's very quick, strong, decisive, good in the air and a big presence defensively. I think Raul possesses both the physical and the ball-distribution qualities which are viewed as essential in modern central defenders.
"What he lacks is experience, and the only way that a young centre-half, who's bound to make mistakes the same as young goalkeepers will do, can get that quality of experience is by playing lots more games. The hard fact is that you learn by mistakes -- when he's got more games under his belt more people will realise that he has all the conditions to succeed as a top-quality defender."
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Nevertheless, it's really only since Rüdiger and Alaba were simultaneously injured that this emerging defensive leader has been restored to the side. In the 1-1 draw with Atlético Madrid in Saturday's derby, Asencio was absolutely tremendous, arguably the match's best player. He was robust in the way he patrolled Atleti's strikers and was lightning-fast with his sprints but showing a calm, "I'm unfazed" demeanour. (Five out of five duels won, robbed possession four times, nobody dribbled past him and 91% pass accuracy).
He's a real newbie, but the Bernabéu fans didn't take long to chant his name -- a rare, almost unheard of, honour for someone who has only just hit double-figure first team appearances. Ancelotti said in admiration: "He was fantastic."
But there's an added irony about the defender being underestimated, especially given who are Madrid's Champions League rivals on Tuesday. It was as recently as last summer that the City Group, Manchester City's parent corporation, which tried to prise him out of Madrid's La Fábrica Academy, for a seven-figure sum. But that plan was merely in order to loan him to Girona (as they did with winger Savinho last season) rather than install Asencio under Guardiola's orders. Madrid's No. 35 immediately, understandably, turned his nose up at the idea.
Now, here he is as one of the main barriers between the 2023 champions and progress into the quarter-finals. Life comes at you fast. As will Haaland at Asencio. We can count on that.