The Bulls led by as many as 14 points late in the second period, but the Spurs closed within five by halftime and then ran over Chicago during the closing 24 minutes.
Duncan and Ginobili both scored 18 points with Duncan adding 10 rebounds and five blocks. Tiago Splitter had 13 points and 10 rebounds for the Spurs, who shot 54 percent and bested the Bulls in the second half 54-31.
Chicago was led by Marco Belinelli with 21 points.
San Antonio has a 24-3 home record this season and is one of four NBA teams with four or fewer losses on their own court -- joining Denver, Oklahoma City and Miami.
Newt Gingrich fires back at Mandela backlash
Campus cop fatally shoots Texas student during traffic stop