Afful's jaw is wired shut and will be for at least four weeks, then the Ghanian international will need to return to match fitness. The injury was suffered in an inadvertent collision with countryman Jonathan Mensah.
The match against Atlanta was Afful's 100th in MLS regular season play. He has been an integral part of the Crew's starting XI since joining during the 2015 season.
The Crew's fullback depth will be thin as during preseason, as Afful joins left back Milton Valenzuela on the injured list after the 20-year-old suffered a season-ending knee injury.