Lionel Messi submitted a transfer request to Barcelona in a dramatic sea change that leaves the Argentine's two-decade stay at the Nou Camp in jeopardy.
Tuesday's stunning announcement has left the world of football in frenzy, but how did we get here and what's the likelihood of Messi actually parting company with Barca?
Here, with the help of Sky Sports News reporters and Spanish football experts, we delve into the inner legal workings of Messi's Barcelona contract, the narrative underlining his transfer request and whether there is a club in world football who could pull off what would be the signing of the century.
What has changed for Messi?
Throughout the years, Messi has not been afraid of voicing his frustrations with the Barcelona board and the direction the club has been taken.
The club's questionable recruitment policy was laid out for all to see at the end of the 2019/20 as Barca relinquished their La Liga crown to eternal rivals Real Madrid before their humiliating 8-2 Champions League exit at the hands of Bayern Munich.
Quique Setien was relieved of his duties in the immediate aftermath and replaced by club legend Ronald Koeman, but Spanish football journalist Alvaro Montero claims an unconvincing first meeting with the Dutchman resulted in Messi tendering his transfer request.
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"The main thing is that the meeting last Friday with Ronald Koeman was not as good as they expected for a football club like Barcelona," he told Sky Sports News. "The meeting with Koeman didn't go well, from Messi's opinion.
"Koeman told him that he didn't count, for example, with players such as Arturo Vidal or Luis Suarez, and Messi didn't like that.
"The way of Koeman treating him in the media and the way he has expressed the way he wants to work in Barcelona, wasn't liked by Messi, so I think that was the situation."
What is Messi's current contract status?
One thing that is crystal clear at this stage is Messi remains contracted to Barcelona until the summer of 2021.
The 33-year-old signed a four-year contract back in November 2017, a deal he claimed made his dream of finishing his career at his "home" Barcelona a reality.
"I'm happy to continue with the club, which is my home. My dream was to finish my career at Barca and we are moving down that path."
Inserted into Messi's contract was a staggering 700 million euro (£626m) buy-out clause that would-be suitors would have to pay in order to lure him away from the Nou Camp.
The clause, coupled with Messi's commitment on renewal, seemed to make a Barcelona exit financially and emotionally unviable, but this week's incredible developments mean it is now more possible than anyone could have imagined.
What about Messi's exit option?
Also inserted into Messi's contract back in 2017 was a clause that states he could leave Barcelona for free at the end of every season should he wish, as Spanish football expert Graham Hunter explains.
"When Messi's last contract was signed, his camp argued for a 'get-out-of-jail free' clause at the end of every season," he told The Transfer Show.
"He had to inform the club in May that he wanted to leave, and they had to allow him to leave for nothing.
"Messi and his people have been prepared to parachute out of a failing football club for a very long time.
"When that clause was inserted it was typical of this club, that they can be told something in big, bold writing and misunderstand it or fail to act on it - just look at the Neymar fiasco."
So Messi can leave for nothing?
With Messi expressing his desire to leave Barcelona, would-be suitors across the globe will be licking their lips at the prospect of securing the greatest free signing in history. In theory that may be the case, but things are not as simple as that.
The coronavirus pandemic and suspension of the La Liga season meant Barcelona finished their campaign in August instead of May.
Barcelona do not agree the clause is still active. It was said to have expired on June 10 - 10 days after the original date of the Champions League final on May 30.
"There is a little bit of confusion because Messi will say the season finished late, and under the contract, when the season finishes, he can leave for free," Sky Sports News reporter Dharmesh Sheth said.
"But Barcelona will say this is an exceptional circumstance that the season got extended and they will refer to when the season should have ended before, which would have been in May or early June.
"They will say that was when the exit clause expired, so the 700 million euro release clause becomes active once more.
"Messi can say he wants to leave Barcelona, but until this release clause issue gets sorted, and whether the can actually leave for free, you have to wonder who can actually pay 700 million euros to buy him?"
What is Messi's camp saying?
Messi's lawyers are arguing that - in the spirit of the deal and good faith - the clause is still active after the rescheduled Champions League final on August 23.
Graham Hunter added: "Messi's camp will argue that although the timing for this clause in his contract has passed, they are going to say this was an odd season, an extended season.
"If months become transferable, they're going to argue that saying [he wants to leave] in August is the same as saying it in May. I'm not sure if that will wash."
Messi and Barca on courtroom collision course?
After a two-decade career at the Nou Camp that has delivered 34 major honours, Messi and Barcelona couldn't split in an acrimonious court battle, could they?
Sky Sports News reporter Kaveh Solhekol fears that may be the case, adding: "I think this is going to end up in a courtroom in Barcelona.
"On the one hand Messi will try to force his way out of the club by saying 'I can leave on a free transfer', on the other Barcelona will say 'no, look at your contract, we demand 700 million euros before you can leave'."
Dharmesh Sheth added: "If that's the case, it's going to be an awful parting of the ways for one of the most pleasing marriages in football - Messi and Barcelona.
"Imagine if it ends up in court, it would be an awful way to finish."
Gaspart: Messi cannot leave
Talk of a courtroom battle is premature at this stage and would represent a strange and ultimately fruitless avenue for the Messi camp to go down, according to Joan Gaspart, former Barcelona president between 2000 and 2003.
"Messi cannot leave," he told Radio Marca. "He will have to leave in 2021. I have seen the contract and it is very clear. The clause ended in June and there is not going back.
"I would prefer him to leave next year for zero than to go now for less than 700 million euros. The club is in charge here, not the player.
"The club paid the players, but this is not a matter of money, there is a signed contract and that's it."
Messi in fact risks a FIFA ban if he leaves Barcelona without resolving his contractual dispute, a leading sports lawyer has claimed.
Nick De Marco QC, who has represented sport's governing bodies, players, clubs and agents since 2002, says world football's governing body is likely to be asked to settle any dispute in the first instance.
"If it ended up anywhere, it would be most likely in the FIFA Dispute Resolution Chamber because Messi, being Argentinian, the FIFA rules would apply, and FIFA has its own set of laws and rules," De Marco, of Blackstone Chambers, told The Transfer Show on Sky Sports News.
"So, it's unlikely to be Spanish law or English law or Swiss law but it would be the FIFA rules that apply, and they have a commission that can determine these things.
"Ultimately, either party can then appeal to the Court of Arbitration for Sport. That's how these sorts of issues are normally dealt with.
"One possibility, and it's certainly not one I'm advising anybody, is a player simply just walks out and says, 'I'm entitled to walk out, so I'm walking out'.
"The risk with that strategy is, although FIFA will normally allow the registration to move with the player, if the club then brings a claim and succeeds, not only is the player liable to [pay] damages but also is likely to be banned under FIFA rules for a period of months and the new club signing him have a transfer embargo.
"It's such a high-risk strategy that, unless you were sure that the player was in the right, it's not a risk one would take."
Is this all just a power play?
By submitting a transfer request, has Messi played the first move in a wider power play at the Camp Nou designed to oust president Josep Maria Bartomeu?
Spanish football expert Terry Gibson believes that may just be the case, with Messi and his camp keen for the club to come under new leadership a year before Bartomeu's tenure is due to expire.
"The situation with the president, Josep Maria Bartomeu, he is going to be leaving the club at the end of next season," he said.
"He can't be elected to stay on for another term and I think this is a power play from Messi and his camp at the very least, if he has any intention of staying at the club, to make sure the president leaves now.
"If there is a choice between the Barcelona supporters of who stays or who goes between Messi and the president, there's only one winner there."
Graham Hunter, however, has highlighted a number of flaws with this alleged strategy, adding: "I think if you view it as a strategy in order to get the president out, think again.
"This president is too stubborn and too obstinate to will try and sit this out and even fight in the courts over this contract, which would be a disgraceful scenario.
"The presidential elections are in a year and I don't think the president will bring them forward, even to save this situation."
How much would Messi cost and who can afford him?
Barcelona may be standing firm on Messi's exit clause but with the Argentine making his intentions clear he wants to leave the question of who can afford to pull off a potential transfer remains.
Manchester City have the resources to finance such a deal, and the prospect of a reunion between Messi and Pep Guardiola at the Etihad would deliver a romantic narrative.
Then there's Paris Saint-Germain, who like City have limitless funds available as they look to secure the missing piece in the jigsaw after falling at the final hurdle in Champions League final.
"Will Messi be able to force his way out of Barcelona? That is the first hurdle he has to clear," Kaveh Solhekol said. "The second hurdle is can he find a club who can afford to pay him?
"When you think about it, how many clubs are there in the world that can afford to pay Messi the kind of money he's on? In the current economic climate, I cannot see another club in the world that can afford to match the money he's on at Barcelona.
"Manchester City chairman Khaldoon Al Mubarak accepted that they normally sign players aged between 20 and 25 but they were willing to make an exception this summer to buy somebody who is a bit more experienced. Messi is 33, does that mean Man City are interested in signing him?
"PSG could afford to sign him as well. They have Kylian Mbappe, they have Neymar and spent £200m getting him out of Barcelona, would they want to Messi as well?"
Alvaro Montero added: "In Spain, on a television programme, they said that Manchester United could be an option. Many people in Italy are saying that Inter could be an option. I don't think so because there is a difference in the financial situation of the Premier League and Italy, France, Spain or Germany.
"Of course, the Premier League is also maybe the best league in the world so I think Premier League plus Manchester City plus Pep Guardiola is a good cocktail altogether.
"We know the union of Pep Guardiola and Messi at Barcelona eight or nine years ago was amazing. Maybe the best team in the world ever. I would say there is a huge possibility of Manchester City and I would say they are the first ones in this race."
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