When Lionel Messi retires from Barcelona, he will leave a hole bigger than any player has left at any club, ever.
It won't just be the goals, assists and trophies that are missing either. There could be a commercial drop-off too. Brands might not be so desperate to pay whatever it takes to associate themselves with the club if they no longer have history's finest.
The club will do its best to cover his departure by shrewd activity in the transfer market, but as club president Josep Maria Bartomeu knows only too well, that can be tough. The plan was for Neymar to be Messi's heir.
Lionel Messi celebrates after finding the back of the net against Levante last weekend
'He had the chance to be the No 1 when Messi went,' Bartomeu told Sportsmail in an interview last season. That did not end well.
'It never worked out that way and we got a lot of money and we invested that in two players, [Philippe] Coutinho and [Ousmane] Dembele,' he said.
But Coutinho is now at Bayern Munich on loan and Dembele was left out of the squad completely for the last league game because Barcelona coach Ernesto Valverde clearly remains unconvinced by him.
Around £250million was spent on Coutinho and Dembele. It wouldn't be too harsh to say it was wasted – it is not going to be easy buying a Messi-less future that allows Barcelona to carry on winning.
Neymar was supposed to become Messi's heir at Barca but he forced through a move to PSG
Debut: Vs Espanyol, October 16, 2004
Honours: La Liga x10, Champions League x4, Cope del Rey x6, Spanish Super Cup x8, UEFA Super Cup x3, Club World Cup x3
Barcelona know they need other ways of filling the Messi void. Xavi coming back as coach is one possible road to take.
Asked if Xavi could even be the successor to the current coach Valverde, Andres Iniesta said last week in an interview with Marca: 'You never know. There have been cases of coaches with no previous experience in Primera [La Liga] who then did very well.
'What a coach needs is to have his ideas very clearly set out. He needs to know what he wants and then he needs a group of players who can then put the ideas into action.'
The smart money is on Ronald Koeman taking over from Valverde at the end of the season which would put Xavi's eventual arrival to the dugout back to 2021 or 2022 by which time Messi will probably have stopped playing.
Xavi could return to Barcelona as manager as the club look to replace one legend with another
Barca president Josep Maria Bartomeu is aware of the challenges the club face without Messi
Xavi has never made a secret of wanting to become a coach and he is probably the only figure in Barcelona's recent past who could fill the vacuum left when Messi's aura ups and goes.
Could Barcelona possibly time things so that one club legend stops playing in the team and another club legend starts managing the side? It would certainly be one way of dealing with the inevitable depression that will follow Messi's last game.
Xavi's arrival would be a symbolic plaster to cover Messi's departure. Economically the club might have to consider other things.
How much Messi's departure will affect Barcelona's finances is open to question. In October members agreed a budget that projected revenue for the 2019-20 season at a record-breaking €1,047m (£902m). Projected spending will reach just over €1,000m (£863m) so there is a slim profit margin. It's the commercial arm of the club that is lifting most weight, bringing in an estimated €374m (£322m). That was up €49m (£42m) on the previous year thanks to more sponsorship deals.
The largest part of the club's spending is taken up by the wage bill set at €507m (£437m). And while it's true that Barcelona might be a slightly less attractive club to sponsor when Messi is no longer there, it's also true that the wage bill will be lighter without the world's top earner on it.
Messi's salary is estimated to be around the €45m (£39m) mark. If that's the hit that is eventually taken on sponsorship streams then there will be nothing gained nor lost.
Messi's retirement could cost the club money in sponsorship - but they will save on his wages
It's also true that any effect will not be felt immediately. The deal with Nike for example runs until