Brandon Moreno is the 1st Mexican born UFC champ ... and the newly crowned flyweight king just received a heartfelt message from Mexico's arguably greatest athlete ever -- and it's impossible for this to not make you feel good.
TMZ Sports recently talked to 58-year-old Julio Cesar Chavez Sr. (he's fighting this weekend) ... and we asked the former boxing superstar if he had a message for Moreno following his historic victory.
We played the message for the 27-year-old "Assassin Baby" ... and it was awesome.
Chavez's message .