Mark Cuban Attends Every Single Mavs G-League Game

Mark Cuban is so hands-on as the owner of the Dallas Mavericks -- he even attends ALL of his teams' G-League games ... so says Kostas Antetokounmpo.

Kostas -- a 2nd round pick in the 2018 NBA Draft -- is the younger brother of "Greek Freak" Giannis Antetokounmpo ... and currently plays for the Mavs' developmental team, the Texas Legends.

The 21-year-old is averaging nearly 10 points and 6 rebounds per game and has a ton of potential -- but when we saw him at LAX, he told us how great it's been playing for Cuban.

"He be at every game, you know?! ... I feel like he's probably the greatest NBA owner because he's always a part of the team, he comes to the trips, he's there at the games."

Of course, Kostas' big bro is killing it right now -- so we asked if he'd ever like to play on the same team as Giannis.

"If that would happen, that would be awesome!"