The first half between two sides seperated by Stoke Aldermoor failed to produce a goal but in the secind half, Greg Rioch's side took the lead through Billy Daniels.
Sphinx, who fielded former Sky Blue Craig Pead, battled back and were level through a goal from Liam Kay but late on, City won the game with Johnson Harris' fourth goal in three pre-season matches.
City are at home on Saturday to Shrewsbury whilst Coventry Sphinx travel to Barwell for the Joe McGorian Cup Final which is played between the Midland Alliance League Cup winners and the Midland Alliance League winners