Darius Rucker's singin' his blues away ... 'cause he hopped onstage in Las Vegas to belt out a few tunes -- alongside Miami Dolphins QB Tua Tagovailoa.
The legendary singer-songwriter was joined by TT for a performance of his song "Wagon Wheel" ahead of Super Bowl Sunday in Sin City ... and the dynamic duo seemed to give the crowd the time of their lives.
Check out the vid .