The Chile international heaped praise on his former coach, while stating that Lionel Messi is a player who has everything
The 23-year-old attacker, who moved to Camp Nou last summer, played under Bielsa during the coach's stint in charge of the Chile between 2007 and 2011.
Speaking ahead of the Copa del Rey final against Athletic, Alexis revealed the influence that the Argentine had on him during the formative years of his career.
"Taking on Marcelo Bielsa is important to me, I learned a lot from him and it is because of him that I am who I am," he told El Mundo.
"What I remember the most about Bielsa was the mentality that he tries his players to have."
The Chile international also noted that he is happy with life in Catalunya and stated that Lionel Messi is a complete player.
"I feel fine at Barcelona, I am learning new things after every training session," Alexis added.
"[Pep] Guardiola teaches me things after every training session, and he also does it with videos.
"Hands up whoever thinks Messi lacks something [as a player]."