Born in Caspe near Zaragoza, Álvaro Sanz came to Barça in 2015 from Zaragoza to live in the Masia Residence - Oriol Tort Training Center and play in Cristian Catena's U16B team, who were proclaimed champion of league that season.
Since then, he has won league titles with U16A (2016/17), U19B (2017/18) and U19A (2019/20). With Denis Silva's U19A, he helped qualify the team for the semifinals of the 2018/19 UEFA Youth League, where Barça lost on penalties against Chelsea (a match that Álvaro Sanz was suspended for).
In the 2019/20 season he played 1,135 minutes with Franc Artiga's U19A side and scored one goal. In the UEFA Youth League he took part in five of the six matches in the first phase.
An international in all the Spanish youth teams, Álvaro Sanz was part of the U19 team that was proclaimed European champion in Armenia after beating Portugal in the final. He has a contract until June 30, 2023 and his termination clause is 10 million euros.
A midfielder trained in La Masia who is strong in defence and who gives balance to the team