Alejo started playing rugby in 1987 in San Isidro Club in infant stage. In 1995, still in primary school, while his brother Matías was playing the Rugby World Cup, his family moved to Punta del Este, Uruguay, where he continued playing rugby defending the colors of Los Lobos Marinos, partner founder of that club and being coached by Pablo Lemoine, former teammate and current coach in the national team. In 1999, he left the club in Punta del Este because it didn't have enough players to form a division according to his age at the moment, and that's why he was transferred to Old Boys in Montevideo, starting at the under-19 team, and debuted there in first division in 2000, with the endorsement of Pedro Bordaberry, coach of that team. In 2003 he returned to San Isidro Club, joining the under-22 team and debuted in first division in 2005, against Atlético del Rósario. Later in September 2005, he made a brief professional experience in the Unione Rugby Sannio, in Italy, returning to SIC in 2007, where it remains currently playing, being a valuable prop and achieving complete his university studies, interrupted by his adventure in Italy.