 Pusineri started his professional football career in 1998 with a local club in Almagro, he had an impressive season of scoring 11 goals in 29 games, he was quickly signed by San Lorenzo where he helped the club to win the Clausura 2001 championship.During his three years with Club Atletico San Lorenzo de Almagro, Pusineri made 61 appearances and scored 11 goals.In 2002, Pusineri was snapped up by Independiente, where he played a part in their championship season in Apertura 2002.