Bombshell revelation from Canelo Alvarez ... the boxing superstar says his brother was kidnapped in Mexico in 2018 -- and he was the one who was forced to negotiate with the scumbags for 3 DAYS to bring him home.
The 30-year-old broke it all down on "In Depth with Graham Bensinger" during an interview that will air in its entirety this weekend ... explaining just days before his '18 fight against Rocky Fielding, he got some terrifying news.
Canelo says shortly after he landed in New York for the fight, he was told one of his older brothers had been abducted.