If he hadn't been at Boulevard Victor-Hugo No. 63, home of the American Hospital of Paris, getting his badly bruised and twisted ankle examined by the experts in whom Paris Saint-Germain have placed their medical faith, then you'd have sworn that Neymar made the Champions League draw on Monday morning -- at least as far as the PSG-Barcelona round-of-16 tie is concerned.

The Brazil international stood in the flash interview zone of Old Trafford a little less than two weeks ago, getting into the spirit of the Theatre of Dreams nickname of United's home, by announcing, with a giggle of hopeful laughter, "What I want most of all is to play with Messi again, to be able to enjoy him once again on the pitch. He can play in my place, I have no problem with that! But I want to play with him next year, for sure. We have to do it next season."

Neymar meant, without any possible doubt, that it was time for PSG to take advantage of Lionel Messi's imminent free-agent status. Just months after he was blocked from leaving for Manchester City, the Argentinian player will be free to openly negotiate with whichever club he wishes in a fortnight's time and then sign for the most attractive of Barcelona's rivals, without any transfer fee, next summer.

How quickly Neymar's wish has come true.

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Rather appropriately, it'll be 48 hours after Valentine's Day that he and Messi can swoon over one another's delicious talents at the Camp Nou -- but in battle, rather than reunited in the same cause, as they both wish to be.

We know that even the quicksilver Brazilian player couldn't have pulled off one of football's greatest sleights of hand to secretly fix Monday's last-16 draw, because on Sunday night, he was the victim of a brutal challenge that left him in tears, fearful for his season and desperate to hear the quiet whirr of an MRS scan on his ankle to give him positive news. Happily, not long after the draw, the French champions were able to announce that Neymar's ankle damage is more likely to be a cause of three or four weeks of inactivity, leaving him perfectly poised to be in scintillating form by mid-February.

I know that this draw means that we'll see endless acres of footage of, statistically at least, the greatest comeback in the history of European Cup football. And, fair play, it was brinksmanship of a kind that Harry Houdini would have called overly showy to lose 4-0 in the French capital and then win 6-1, practically with the last kick of the ball, at Camp Nou in order for Barcelona to eliminate Les Rouge et Bleu the last time these Eurocrats met nearly four years ago.

But there's a hidden narrative in the intertwined fates of these two clubs. It revolves around Neymar and Messi.

Five out of the six times they've met competitively, the Catalans have triumphed. The most painful, without question, was when PSG were competing to retain the first European trophy they'd ever won in their short, 26-year existence. It was May 1997, and a penalty scored by Ronaldo -- the third-last goal he'd ever notch for Barca -- meant Sir Bobby Robson's team won the Cup Winner's Cup, not Les Parisiens.

So when Unai Emery's apparently all-conquering French champions took a four-goal lead from the Parc des Princes to the Catalan capital in 2017, you wouldn't have needed to be a Parisian with an exceptionally long memory to be ready to gleefully shout: "La revanche est a nous!" ("Revenge is ours!") Of course, football is a quixotic mistress, and Parisian hopes were guillotined by an enormous Barcelona performance and some remarkable lack of moral fibre from Emery's men, who largely wilted.

However, that's not the whole story.

When Edinson Cavani scored a corker with 28 minutes left, he made it 3-1 on the night but 5-3 to PSG on aggregate. It meant that Barcelona were obliged to score three more goals or be knocked out. That remained the state of affairs until the 88th minute -- 120 seconds, plus any added time, and Barcelona desperately needed three goals. It was as Herculean a task as you can imagine -- unless you've literally been ordered to clean the stables of King Augeas, whose horses are immortal and produce an enormous, never-ending supply of dung.

But Neymar proceeded to produce the greatest six minutes of his footballing life: from a truly divine free kick (yes, Messi let him take it) in the 88th minute, through his nerveless penalty and then a Phil Mickelson-like lob-wedge pass right onto Sergi Roberto's outstretched boot for the winner on 94:48 -- there were 12 seconds of added time remaining. There are few, if any, better examples of one man taking an impossible task, against impossible odds, and making it happen.

Watch the scenes again on YouTube if you want. It's the kind of bedlam that football was invented to create. Nobody is conscious of their actions and visiting players are dazed, completely unsure what has happened. Barcelona's players and staff are, literally, imitating headless chickens -- sprinting off in one direction, changing course seconds later, bumping into one another, appealing for mutual confirmation that what they think they've seen actually happened.

No matter the mayhem, it was Neymar's night.

However, the image that immediately came to symbolise this unsurpassed comeback, because of the photographic brilliance of its composition and who the picture contains, was of Messi. Not Neymar.

You know the one. Taken by a Mexican freelance photographer Santiago Garces, it instantly became the most viewed image of Messi that Barcelona had ever published across all of their social media. While other combatants are still flat out or running crazily across the playing surface, Messi has sprinted behind the goal into which Sergi Roberto has just scored and is standing, alone, on top of one of the advertising hoardings, silhouetted against the night sky, right arm with clenched fist raised high above his awestruck face. What makes the startling image extra special is that Garces (who says, "I believed that Barcelona could stage the fightback and so I stationed myself among the fans behind the goal") is hunched down so that a jubilant group of supporters are perfectly framing Messi's magisterial, king-of-all-I-survey pose.

Dressing room and training ground legend suggests that with Neymar already unsure about whether he needed to strike out on his own in order to be regarded as a Ballon d'Or winner, to surpass his friend and teammate as the world's No. 1, the fact that on the night of his greatest individual feat, it was still Barcelona's No. 10 whom the world worshipped helped seal his decision. Seven official Barcelona matches later -- four while sealing the Spanish title, two while comprehensively exiting the Champions League to Juventus in the next round, and then a tepid Copa del Rey final victory over Alaves -- and Neymar was gone.

It has proved a pyrrhic decision for all concerned. Messi lost someone vitally important -- spiritually and sportingly. Barcelona's decline was first gradual, now rapid.

For Neymar, there have been moments, but none of the kind he truly craved. There's been no Champions League win, no springboard toward winning the 2018 World Cup, not even a sniff of a Ballon d'Or.

Messi, today, is fresh from witnessing what can be achieved in later life if you choose well, keep your mentality ruthlessly focussed and play with a well-constructed squad -- a reminder that Cristiano Ronaldo delivered with some panache at Camp Nou last week. That, without question in my mind, will have helped seal Messi's realisation that either he settles for short-term mediocrity while Barcelona rebuild or he changes club for the chance of greater fulfilment and bigger victories as he moves through his middle and late 30s. It's not a time to be messing about for any footballer, let alone the greatest ever.

In January, Barcelona will elect a new president. Whomever it is might well have recruited Xavi to become general manager by the time PSG visit in February with a view to the Catalan succeeding Ronald Koeman come June. Whether the new regime is truly desperate to keep Messi or discretely content to shed the breathtaking financial outlay it takes to keep him will remain a point of debate for a long time to come. In any case, what Neymar and PSG do against Koeman's Barcelona could well become fundamental to what Messi opts to do next with his (still) outrageous talents.

One minor note of dark humour remains.

Neymar, for reasons only he can truly understand, has found a way for several years now to be unable to play around the middle of March (injury, suspension, temporary furlough) so that he could attend both his sister's birthday and the Rio Carnival. The return leg of this wonderful tie will be in Paris on March 10, the day before Rafaella's birthday.

With what's at stake, with Neymar desperate to persuade Messi to abandon his Mediterranean idyll and come join him in chilly Paris, never mind desperate to eliminate Barcelona and get one over on the club with whom there's been threat of lawsuit and countersuit since he left in 2017, Rafaella and the Carnival might have to do without PSG's talisman this year. But for a worthwhile cause.