Canelo Alvarez didn't let a hard-fought battle in the ring keep him from singing his heart out at the club on Saturday -- the boxing superstar hit up a Vegas club for some amazing karaoke after losing to Dmitry Bivol ... and TMZ Sports has the vid!!
Alvarez was in great spirits just hours after going up against the undefeated Russian boxer at his his official Hennessey afterparty at Resorts World's Zouk nightclub ... singing along to Mexican hits like his go-to song, "Eso y Más" by Joan Sebastian.
This is pretty much a tradition at this point -- Canelo serenaded his wife, Fernanda Gómez, at the same club after he beat Caleb Plant back in November ... wowing the crowd with his pipes.
Of course, Canelo went up a weight class to take on the hardest challenge he could realistically fight ... and while it didn't go his way, he gave it everything he had for 12 rounds.
We're told Canelo and his crew rolled in around 2 AM and enjoyed bottle service for a few hours ... with the boxer singing for all to hear for about 30 minutes -- with a special appearance by actor Diego Boneta!!
Alvarez is known to be humble in both victory and defeat ... and this video further proves it.