A lifelong supporter of Newell's Old Boys, Messi joined the Rosario club when he was six years old. During the six years he played for Newell's, he scored almost 500 goals as a member of "The Machine of '87", the near-unbeatable youth side named for the year of their birth, and regularly entertained crowds by performing ball tricks during half-time of the first team's home games.
As the Messi family had relatives in Catalonia, they sought to arrange a trial with Barcelona in September 2000. First team director Charly Rexach immediately wanted to sign him, but the board of directors hesitated; at the time it was highly unusual for European clubs to sign foreign players of such a young age.On 14 December, an ultimatum was issued for Barcelona to prove their commitment, and Rexach, with no other paper at hand, offered a contract on a paper napkin.
Messi scored his first senior goal on 1 May 2005, against Albacete, from an assist by Ronaldinho, becoming – at that time – the youngest-ever scorer for the club.
On 10 March 2007, Messi scored his first hat-trick in a Clásico, the first player to do so in 12 years, equalizing after each goal by Real Madrid to end the match in a 3–3 draw in injury time.
After two unsuccessful seasons, Barcelona were in need of an overhaul, leading to the departure of Rijkaard and Ronaldinho. Upon the latter's departure, Messi was given the number 10 shirt. He signed a new contract in July 2008 on an annual salary of €7.8 million, becoming the club's highest-paid player.
After victories in the Supercopa de España and UEFA Super Cup in August, Barcelona won the FIFA Club World Cup against Estudiantes de La Plata on 19 December, with Messi scoring the winning 2–1 goal with his chest. Achieving six trophies this season.
La Masia, the FC Barcelona academy, achieved a record-breaking honor in becoming the first youth academy ever to have all three finalists for the Ballon d'Or in one same year, with Lionel Messi, Andrés Iniesta and Xavi. Messi won the award, his second consecutive Ballon d'Or victory.