<P> After a year at Barcelona's youth academy, La Masia, Messi was finally enrolled in the Royal Spanish Football Federation (RFEF) in February 2002 . Now playing in all competitions, he befriended his teammates, among whom were Cesc Fàbregas and Gerard Piqué . After completing his growth hormone treatment aged 14, Messi became an integral part of the "Baby Dream Team", Barcelona's greatest - ever youth side . During his first full season (2002--03), he was top scorer with 36 goals in 30 games for the Cadetes A, who won an unprecedented treble of the league and both the Spanish and Catalan cups . The Copa Catalunya final, a 4--1 victory over Espanyol, became known in club lore as the partido de la máscara, the final of the mask . A week after suffering a broken cheekbone during a league match, Messi was allowed to start the game on the condition that he wear a plastic protector; soon hindered by the mask, he took it off and scored two goals in 10 minutes before his substitution . At the close of the season, he received an offer to join Arsenal, his first from a foreign club, but while Fàbregas and Piqué soon left for England, he chose to remain in Barcelona . </P> <P>--Barcelona's then assistant coach Henk Ten Cate on Messi's first - team debut . </P> <P> During the 2003--04 season, his fourth with Barcelona, Messi rapidly progressed through the club's ranks, debuting for a record five teams in a single campaign . After being named player of the tournament in four international pre-season competitions with the Juveniles B, he played only one official match with the team before being promoted to the Juveniles A, where he scored 18 goals in 11 league games . Messi was then one of several youth players called up to strengthen a depleted first team during the international break . French Winger Ludovic Giuly explained how a teenage Leo caught the eye in a training session with Frank Rijkaard's first team: "He destroyed us all...They were kicking him all over the place to avoid being ridiculed by this kid, he just got up and kept on playing . He would dribble past four players and score a goal . Even the team's starting centre - backs were nervous . He was an alien ." At 16 years, four months, and 23 days old, he made his first team debut when he came on in the 75th minute during a friendly against José Mourinho's Porto on 16 November 2003 . His performance, creating two chances and a shot on goal, impressed the technical staff, and he subsequently began training daily with the club's reserve side, Barcelona B, as well as weekly with the first team . After his first training session with the senior squad, Barça's new star player, Ronaldinho, told his teammates that he believed the 16 - year - old would become an even better player than himself . Ronaldinho soon befriended Messi, whom he called "little brother", which greatly eased his transition into the first team . </P> <P> To gain further match experience, Messi joined Barcelona C in addition to the Juveniles A, playing his first game for the third team on 29 November . He helped save them from the relegation zone of the Tercera División, scoring five goals in ten games, including a hat - trick in eight minutes during a Copa del Rey match while man - marked by Sevilla's Sergio Ramos . His progress was reflected in his first professional contract, signed on 4 February 2004, which lasted until 2012 and contained an initial buyout clause of € 30 million . A month later, on 6 March, he made his debut for Barcelona B in the Segunda División B, and his buyout clause automatically increased to € 80 million . He played five games with the B team that season but did not score . Physically he was weaker than his opponents, who were often much older and taller, and in training he worked on increasing his muscle mass and overall strength in order to be able to shake off defenders . Towards the end of the season, he returned to both youth teams, helping the Juveniles B win the league . He finished the campaign having scored for four of his five teams with a total of 36 goals in all official competitions . </P>

When did messi started playing for barca first team