Swin Cash had 14 points, eight rebounds and six assists for Detroit, which has won four straight.
Kara Braxton scored 12, and Deanna Nolan added eleven for the reigning WNBA champions.
The Shock hold a four-and-a-half game lead over second-place Indiana in the Eastern Conference with six games remaining.
The Shock's only loss in the past seven weeks was a 83-73 home loss to Chicago on July 26th.
Jia Perkins scored 19 for Chicago, who lost for the third time in four games. Stacey Dales added 14 for the Sky, who are tied with Washington for the fourth and final playoff spot in the East.
Chicago leading scorer Candice Dupree missed the game to attend her grandmother's funeral in Florida.