answers: 17
context: all competitions surpassed Gerd Müller’s 67 goals in the 1972–73 Bundesliga season, making him the single-season top scorer in the history of European club football. Under manager Tito Vilanova, who had first coached him aged 14 at "La Masia", Messi helped the club achieve its best-ever start to a La Liga season during the second half of 2012, amassing 55 points by the competition's midway point, a record in Spanish football. A double scored on 9 December against Real Betis saw Messi break two longstanding records: he surpassed César Rodríguez's record of 190 league goals, becoming Barcelona's all-time top scorer </s> Aware of his physical limitations, Messi employed a personal trainer to increase his muscle mass, returning to the squad in an improved condition in time for the World Youth Championship, hosted by the Netherlands in June 2005. After he was left out of the starting line-up in their first match against the United States, a 1–0 defeat, the squad's senior players asked manager Francisco Ferraro to let Messi start, as they considered him their best player. After helping the team defeat Egypt and Germany to progress past the group stage, Messi proved decisive in the knockout phase as he scored </s> October, his first official goal for Argentina in two-and-a-half years. Under Sabella, Messi's goalscoring rate drastically increased; where he had scored only 17 goals in 61 matches under his previous managers, he scored 25 times in 32 appearances during the following three years. He netted a total of 12 goals in 9 games for Argentina in 2012, equalling the record held by Gabriel Batistuta, Argentina's all-time top scorer, for the most goals scored in a calendar year for their country. His first hat-trick with the "Albicelestes" came in a friendly against Switzerland on 29 February 2012, followed by two more
question: how old was lionel messi when he made his debut for barcelona