All of Johnson's points came in the first half as the Hawks built an early lead and coasted the rest of the way, leading by as many as 27 points. The Grizzlies, who won their opener at Houston on Tuesday night, never led against Atlanta.
Josh Smith had 13 points for the Hawks, while first-round draft pick Shelden Williams finished with 12 points and nine rebounds. Marvin Williams added 11 points for Atlanta.
For the second straight night, first-round draft pick Rudy Gay led the Grizzlies in scoring with 15 points, while rookie forward Alexander Johnson added 13. Kyle Lowry, the rookie guard from Villanova, finished with 12 points, shooting 10-of-14 from the free throw line. Chucky Atkins and Brian Cardinal each had 10 points for Memphis.
Second-year forward Lawrence Roberts logged 35 minutes for Memphis, grabbing 11 rebounds.
Hawks center Lorenzen Wright and Grizzlies reserve Kimani Ffriend were ejected late in the third quarter for fighting. The two faced off under the Grizzlies basket and got into a shoving match until Cardinal stepped in and pulled Wright, who played the past five years with Memphis, away from the fracas.
Atlanta led 60-40 at halftime.
The Hawks built a 22-point lead in the first half thanks to poor ball-handling by Memphis. The Grizzlies committed nine turnovers in the first 6 minutes, while missing five of their first six shots.
The Grizzlies' 15 turnovers for the half led to 21 Atlanta points.
Hawks guard Lionel Chalmers did not make the trip after injuring his right ankle. He will not play in Friday's game against Houston in Little Rock, Ark.