Trey Songz -- DESTROYED ON THE COURT ... By Street Ball Legend

Trey Songz just learned the hard way what it's like be completely DOMINATED on the basketball court -- thanks to a legendary street baller.

The R&B singer was playing in the Power 106 All-Star Celebrity Basketball Game in L.A. this weekend -- which raised money for a charity that rehabilitates former gang members.

But one body definitely hit the floor on the court -- when Songz (an avid basketball player) tried to guard Bone Collector ... one of the most famous street ballers in the country.