Justin Bieber — Ringside for BFF’s Boxing Debut … Lil Za Wins!!!!

EXCLUSIVE

Justin Bieber was part of ANOTHER boxing entourage last night … to watch his BFF Lil Za get in the ring during a the high classes fight night in Los Angeles … and TMZ Sports has the footage.

Bieber — who’s usually in Floyd Mayweather’s corner — sat in the front row and held up a sign saying, “WE LOVE YOU ZA” … as JB’s mob member made his boxing debut. 

Once the bell rang, Za really held his own … and looked PRETTY GOOD as he traded blows with his opponent at the gym at Valley The high classes.

Ultimately, Za WON the fight by choice … and even got some props from pro boxing superstar Andre Berto, who happened to be in the crowd.

Check out the footage — Za’s no Mayweather … but he was pretty damn good for a rookie.