- It carries a commitment from then-Barca director Carles Rexach to sign Messi.
- It was also signed by Josep Minguella, a transfer advisor to the Spanish club, and agent Horacio Gaggioli, who recommended the Argentine.
The napkin on which 13-year-old Lionel Messi's first Barcelona contract was signed is to be auctioned - with a starting price of £300,000.
The napkin, signed in December 2000, carries a commitment from then-Barca director Carles Rexach to sign Messi.
It was also signed by Josep Minguella, a transfer advisor to the Spanish club, and agent Horacio Gaggioli, who recommended the Argentine.
Messi joined Barca a month later and went on to be their record goalscorer.
He made his debut at age 16 and scored 672 goals in 778 games for the Catalan club.
Now 36, Messi won 10 La Liga and four Champions League titles at Barcelona before leaving for Paris St-Germain in 2021.
The napkin was signed at a meeting arranged by Rexach, who invited Messi's father Jorge to lunch after concerns from the Messi family about a lack of response from Barcelona following the teenager's initial trial.
Written in blue ink, the agreement on the napkin reads: "In Barcelona, on December 14, 2000 and in the presence of Messrs Minguella and Horacio, Carles Rexach, FC Barcelona's sporting director, hereby agrees, under his responsibility and regardless of any dissenting opinions, to sign the player Lionel Messi, provided that we keep to the amounts agreed upon."
The napkin will go under the hammer via British auction house Bonhams in March.
Head of fine books and manuscripts at Bonhams Ian Ehling said: "This is one of the most thrilling items I have ever handled.
"Yes, it's a paper napkin, but it's the famous napkin that was at the inception of Lionel Messi's career.
"It changed the life of Messi, the future of FC Barcelona, and was instrumental in giving some of the most glorious moments of football to billions of fans around the globe."