It all boils down to time.
Soccer competitions need more time to be completed than the roughly two weeks allotted for the Summer Games. The big tournaments, such as Copa America and the World Cup, take a month to complete, so with less time budgeted for the Games, it makes sense to get a head start.
The men's soccer tournament will start on July 24 and run all the way to Aug. 9, while the women's tournament begins July 25 and ends Aug. 10. By doing so, the format ensures group matches, quarterfinals, semifinals and medal games for the Olympic soccer competition.