Last week we opened a portal into a different dimension: one in which Lionel Messi plays form someone other than Barcelona.

His Barcelona contract expires in June of 2021 and, according to reports in Spain, he has broken off extension talks and is considering his future. Messi is apparently unhappy with the club's front office, the players recruited around him and the drip-drip-drip of leaks that depict him as some kind of behind-the-scenes power broker, influencing most of Barcelona's recent (and mostly poor) decisions. That is pretty much all we have right now. Messi's camp has not commented and Barcelona's only comment was president Jose Maria Bartomeu saying that the club had an obligation to renew his contract and that the player himself had said "many times" that he wants to retire at the Camp Nou.

Still, there is no escaping the reality that in less than 12 months he will be a free agent and he hasn't committed past that point. And, until he does, it's more than implicit that he is considering the possibility of being elsewhere come July 1, 2021.

Still, the prospect of him leaving feels flimsy even before you consider all the other factors. Like the fact that the 33-year-old Messi has been at the club since he was 13 and has never seriously hinted at a desire to leave.

Or the fact that if Bartomeu and the front office are part of the problem, there's a good chance they will be gone by 2021; the president's term expires and he will not seek re-election and every indication is that, whoever replaces him, there will be a major shake-up.

Or, indeed, Messi's salary which is somewhere north of $70 million when factoring in bonuses and image rights, meaning he either takes a massive pay cut or you can count on one hand the number of clubs who can afford him.

- Marcotti: How Messi's playing style has evolved
- Missed anything? Latest from Europe's top leagues
- Stream FC Daily on ESPN+ (U.S. only)

And yet, the mere possibility of a Messi move is enough to send tremors. Particularly since, unlike the other seismic GOAT candidate move, if Messi runs down his contract, he won't leave for a €100 million fee like Cristiano Ronaldo did when he joined Juventus from Real Madrid in 2018, but rather as a free agent.

The single biggest factor is that Messi has to want to do this. And for somebody to want to leave a club after two decades, during which he has won everything at club level and is still the reigning Ballon d'Or? Well, it's going to take a lot.

Either he finds a sudden wanderlust and desire to take on new challenges in unfamiliar countries (that would be a side previously unseen; a famously private person, every account depicts Messi as a homebody interested in little outside of football and family), or Barcelona become such a mess that, at 34 (the age he turns six weeks before his deal expires), he no longer wants to put up with it.

There is no other realistic scenario. Nobody is going to make Barcelona an offer they cannot refuse. Nobody at the club feels he's no longer good enough. Nobody wants him gone. It has to come from him.

But suspend disbelief for a minute. Alight at Speculation Station. If Messi does take this momentous decision, where does he go?

For starters, it would be a choice driven by heart (possibly a broken one) and not a desire to pad his stats or ample bank account. That means he would likely be OK with playing for less money. It also makes it hugely unlikely he would join a Barcelona rival. Beyond that?

The romantic choice would be a return to Argentina and his first club, Newell's Old Boys. A bit like when Carlos Tevez went home to Boca Juniors, forsaking the riches and spotlight offered by Juventus. Perhaps Messi is one of those people who leave home to seek fame and fortune elsewhere, then feel the pull of their roots. The fact that a World Cup takes place fewer than 18 months later -- likely his last crack at the game's biggest prize -- would only fuel the narrative.

Less romantic, but potentially more historically transformational, would be a move to Major League Soccer, perhaps Inter Miami. There is a parallel with (Miami co-owner) David Beckham joining the LA Galaxy in 2007 in terms of fame and celebrity, but this would surpass that; the last time a legitimate GOAT candidate played in North America was Pele in the 1970s with New York Cosmos.

With the 2026 World Cup set to take place in North America, which implies more money flowing into the game regionally, plus rumours of a merger between MLS and Liga MX, and the league's own natural expansion, Messi would be the accelerant that finally puts the league over the top.

Then there is the absolute wild card, the fantasy few can fathom, the ultimate crossover: What if Messi teamed up with the yin to his yang, Ronaldo? What if, for the first time in history, some lucky team lined up with two unquestioned candidates to be called the game's greatest-ever player?

Unless he extends his deal at Juventus, Ronaldo will have a year left in the summer of 2021 and will have just turned 36. Might there be a scenario where the curiosity and fascination -- from him and Messi -- stokes the imagination to do something unprecedented and team up with each other's eternal arch-rival?

We are talking about two men, who have achieved everything there is to achieve in club football, who are automatic choices in the conversation of the greatest ever, who have transcended their craft and who have ridden the wave of globalisation and commercialisation that took over football over the past decade. Their place in history was secured long ago, but might this be the final step that takes them beyond the reach of all future contenders?

What would it take for Messi and Ronaldo to team up? Substantial pay cuts for one, at least in terms of guaranteed wages. That said, having the two greatest draws in world football in one place would drive commercial revenue and sponsorship through the roof.

It would not necessarily have to be at Juventus; maybe there would be another landing spot. Maybe other free agents might join them, just for the chance to say they wore the same shirt for that memorable era when Leo and Cristiano teamed up.

Folly? Sure. But it is not wholly unprecedented in another sport. Gary Payton and Karl Malone are in the basketball Hall of Fame and, in 2003, both took less money to join the Los Angeles Lakers and team up with Shaquille O'Neal and Kobe Bryant.

Back to reality. Even if every single sign did not point to the fact that, come what may, Messi will retire as a Barca player, there are counterarguments to each scenario. A return to Rosario and Newell's would also mean subjecting himself to a different sort of pressure, the sort he faces every time he pulls on an Argentina jersey. It would also mean not having the luxury of a stellar supporting cast.

Going from Messi to Messi-ah in the United States is something that appeals to outsize extroverts, who love their celebrity status, like Beckham or Zlatan Ibrahimovic, but Messi avoids the spotlight and is private and shy; you cannot see going on Good Morning America or turning into an spokesperson for the sport. As for the Cristiano tag-team? I don't know where to begin.

But these scenarios do matter because they represent the sort of leverage Messi has vis-a-vis Barcelona. If nobody believes he is ever going to leave, the club can take him for granted. If the stories are accurate and if -- like the vast majority of Barca fans -- he is unhappy with the club's direction, a credible threat of departure is the only tool to make his voice heard.

For him, that becomes increasingly important because whether, it is two, three, five or seven, these are the final years of his career. Every game that passes takes Messi a step closer to the moment when he can no longer do what he loves most: playing football.