NBA's Luka Doncic Raged His Face Off At Miami Hot Spot For 21st Birthday

Luka Doncic might have lost his Mavericks game on his 21st birthday ... but he DEFINITELY won the after-party!!!

TMZ Sports has learned the NBA superstar got after it Friday night for his bday despite losing to the Heat ... hitting up Miami hot spots with his Mavs teammates and other celebs.

We're told Doncic and the guys got dinner at Papi Steak in Miami Beach before ultimately spending the night at Club LIV.

And, you can see in photos we obtained of the festivities ... Doncic was having a blast -- even at one point getting some partying in with Bad Bunny!!

We're told Mavs owner Mark Cuban threw an especially big bash for his team's best player ... taking over LIV's stage area and popping champagne all night.

As for how the hangover went ... the Mavs were off Saturday -- but Luka still took Dallas' game off against the Timberwolves on Sunday.

The team says it was because of a previous thumb injury ... but we're not so sure we're buying that.