Mike Krzyzewski's grandson -- a member of the Duke U basketball team -- was busted for DWI early Sunday morning ... along with his future NBA star teammate, Paolo Banchero, who was also cited for aiding and abetting.
TMZ Sports has confirmed that 20-year-old Michael Savarino was pulled over by the North Carolina State Highway Patrol around 1:10 AM in Orange County, NC ... after cops say he blew a stop sign.
During the traffic stop, police say Savarino -- whose mom is Coach K's oldest daughter -- showed signs of impairment .