This is the most important napkin in FC Barcelona’s history. By signing this piece of paper 23 years ago, a young Leo Messi first pledged to join the club.

The napkin is now set for auction. Per Spanish newspaper La Vanguardia, bids are to start at $380,000, but it could fetch as much as $650,000.

It has been put up for auction by its owner, Horacio Gaggioli, who was Messi’s agent at the time. It is to be sold by the auction house Bonhams.

Messi added his signature to the napkin during a lunch at a Barcelona tennis club in December 2000, when the Argentine was just 13 years old.

With Messi’s father pushing Barça to commit to his son in writing, club chiefs Carles Rexach and Josep Maria Minguella also signed the napkin.

Then-Barça president Joan Gaspart had initial doubts about adding Messi to the club’s youth set-up, given the growth problems he suffered as a child. 

However, the club gave him a two-week trial - and within 10 minutes of watching him play, Rexach and Minguella knew they had to sign him.

The historic napkin was offered to Barça’s club museum, but a deal couldn’t be reached and the document has been sitting in a safe in Andorra.