Spain held an eight-point lead at the half and extended it to 12 by the end of the third quarter, but Great Britain fought back with an outstanding offensive effort in the fourth quarter before eventually falling just short of victory.
Deng added nine rebounds and seven assists to go with his 26 points. Joel Freeland also had a big night for Great Britain, scoring 25 points. Jose Calderon led Spain with 19 points, while Pau Gasol scored 17.
Great Britain fell to 0-3 in the Olympics, while Spain improved to 3-0.