It's hard to imagine Lionel Messi playing for anyone but Barcelona, isn't it?

Since making his debut for the club aged 17, Messi has gone on to score 518 goals and 615 appearances and has claimed 29 trophies along the way.

That's before you consider his personal accolades, too, where he has won the FIFA Ballon d'Or award five times.

Still, with his contract running out in the summer of 2018, plenty of curious eyes are casting a glance towards the Catalan club and rumours that Messi may fancy a new challenge are beginning to carry some weight.

The natural link that Messi has been consistently subject to is a reunion with Pep Guardiola at Manchester City, a club who could ostensibly afford him.

While that narrative has some plausibility to it coupled with the dwindling contract, Marca have revealed why Messi may not have signed his new deal yet.

Back in 2013, during the Sandro Rosell era, the club introduced a system that means the net debt for any one season cannot be more than double the EBITDA, which is the indicator of the gross income, before taxes, depreciation and not including write-offs.

The idea is designed to help the club chip away at the massive debt they have while remaining competitive.

As such, the club's potential signings - rumoured to be Marco Verratti, Hector Bellerin and Ousmane Dembele - and Lionel Messi's renewal aren't likely to be completed until the end of June.

So, any new deal for Messi is likely be announced in July along with any of their transfer business.

City's chief executive Ferran Soriano also believes that Messi will remain in Barcelona for the foreseeable future at least, dismissing their chances of prizing him away.

He told Chinese news agency Xinhua when asked about Messi joining City: "No. I don't think so. I know Messi very well. He and his family are my good friends.

"I think he has settled in Barcelona, and he has been in Barcelona all his life. Naturally, we think he will finish his playing career in Barcelona.

"At least next year, maybe he can finish that career. After that, he can go to China or US, but now I think he will stay in Barcelona."