Is Messi's blockchain interest a sign .............

From numbers on shirts to goal-line technology, the football industry has never been slow to adapt to new ideas and technologies.

More recently, Video Assistant Referees (VAR) have emerged, while fan apps bring playing content and commercial products to supporters off the field of play.

Now the sport - if a little tentatively - is starting to dip its boots into the world of crypto-currency and its supporting blockchain technology.

Earlier this year English Premier League club Arsenal became the first major football club to sign a deal to promote a crypto-currency. It reached an agreement with the gaming company CashBet to advertise its CashBet Coin - used for gambling - at Arsenal's home league games.

Crypto-currencies are a medium of financial exchange, a form of digital cash. There are reckoned to be about 1,500 of them in existence.