 Larrosa started his career at Boca Juniors in 1967, but he was soon allowed to leave by the club.He played for Argentinos Juniors for the 1969 season and although the team struggled, Larrosa played well and was invited to return to Boca.In the 1970 season Larrosa won his first trophy although he didn't actually play in the final of the Nacional against Rosario Central.