A napkin Lionel Messi signed when he was 13 years old to agree to join Barcelona is being auctioned in March by the British auction house Bonhams, with an opening bid of £300,000.

The story of how Messi came to join Barcelona is unique. In 2000, Barcelona scouts spotted Messi’s talent while he was playing in Argentina. Messi’s father Jorge arranged a meeting with Barcelona’s head of youth recruitment Carles Rexach. Rexach was so impressed with Messi’s skills that he decided to sign him right away, using a napkin from a nearby tennis club as an impromptu contract since he had no other documents.

The napkin states that despite any objections, Rexach, in his role as sporting director, agrees to sign Messi pending an agreed upon salary. This deal was later ratified by then-president Joan Gaspart. A month later, Barcelona officially signed the 13-year old Messi, beginning a 20-year association.

Messi and his family moved to Barcelona where he entered the famed La Masia youth academy. Barcelona also paid for Messi’s treatment for a growth hormone deficiency that his family could not afford. Through La Masia, Messi quickly became one of the most promising young footballers in the world.

The 8-time Ballon d’Or winner helped Barcelona win 35 titles in 782 appearances, scoring 674 goals and cementing his status as one of the greatest players of all time.