While at Harvard, Duncan co-captained the varsity basketball team and was named a first team Academic All-American. From 1987 to 1991, Duncan played professional basketball, mostly in Australia, with teams including Melbourne's Eastside Spectres, of Australia's National Basketball League. Duncan also participated in the 2012, 2013, and 2014 NBA All-Star Weekend Celebrity Games. Comedian Kevin Hart conceded the 2014 MVP of the Celebrity game to Duncan (20 points, 11 rebounds, 6 assists). The 20 points are a Celebrity Game high.