Luka Doncic Is The Mavericks' G.O.A.T.

Dirk Nowitzki's time as the greatest Dallas Maverick ever has come to an end ... Luka Doncic now holds that crown -- so says the NBA legend himself!!!

The ex-Dallas great made the revelation to TMZ Sports while heading into Staples Center on Sunday to catch the Mavs-Clippers Game 7 ... and, yeah, it's BIG praise!!!

"He's playing unbelievable," Dirk said after explaining Luka "already has" eclipsed him as the greatest Mav ever.

Of course, Luka went on to lose the big game against the Clips in front of Dirk ... but the 22-year-old arguably STRENGTHENED the big man's claim despite the L.