The napkin was signed in December 2000 when Carles Rexach, then Barca’s sporting director, agreed with agent Horacio Gaggioli to recruit the Argentine teenager who went on to become the club’s all-time top scorer.

The pivotal moment in football history happened after Rexach and Gaggioli met to have lunch after Messi’s father Jorge had become concerned at the lack of response following his son’s initial trials at the Spanish club.

“In Barcelona, on 14 December 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,” is written on the napkin from the Pompeia tennis club.

The agreement, ratified by then club president Joan Gaspart, was formally signed that same night and a month later Barcelona completed the signing of Messi to begin his 20-year stay at the Catalan club.

The eight-time Ballon d’Or winner helped Barca win 35 titles, making a record 782 appearances and scoring 674 goals.