Johnson has been ruled out for Wednesday's contest against the Heat with a left ankle sprain, Kevin Chouinard of the Hawks' official site reports.
Though Atlanta recalled Johnson from the G League's College Park Skyhawks earlier in the day, the rookie won't be an option off the bench Wednesday while he tends to the injury. His absence shouldn't affect Atlanta's rotation, as he's made just one two-minute appearance since clearing the NBA's COVID-19 health and safety protocols last Friday.