Lionel Messi: Who can afford to sign Barcelona striker?

And Real Madrid and Manchester United would struggle to pay Messi's wages without breaking Uefa's rules.

The rest of Europe's elite would have to stagger a payment over a number of years to meet the £170m valuation.

"With the revenue they generate and cash reserves, only United and Real Madrid could pay the fee," said Rob Wilson of Sheffield Hallam University.

"With salary costs probably even they couldn't stay within FFP."

Messi's contract does not expire until 2019 and Wilson said it would be unlikely that Barcelona would accept a staggered transfer payment.

"Unless Messi absolutely wanted to get out of the club, why would Barcelona agree to that?

"Staggering the payments would certainly make it easier for Chelsea, Manchester City, PSG and Bayern Munich but Manchester United demanded the fee up front when they sold Cristiano Ronaldo and I strongly suspect it would be the same for Messi," Wilson said.

There is no suggestion Real Madrid are interested in replicating the controversy created by their decision to sign Luis Figo from Barcelona in 2000.

But Messi, 27, has been the subject of increasing speculation.

He was left out of the Barcelona starting line-up for the defeat at Real Sociedad, subsequently began following Chelsea on Instagram and his future was the subject of a vague comment   by coach Luis Enrique.

Yet the days when clubs merely had to decide whether they could afford a financial package for a player are over.

(BBC)