Roy Hibbert added 12 points and 11 rebounds, and David West and Lance Stephenson also had 12 points each to help the Pacers improve to 7-3 — matching their best start since 2005-06. Indiana also is 4-0 at home for the first time since winning its first seven home games in 2002-03.
Granger was 9 of 16 from the field, including 3-of-5 shooting from 3-point range.
Granger and Hibbert scored all the points as the Pacers, up 53-50 at the half, put together a 16-2 run in the third quarter to make it 71-54 with 5:07 to go in the period.
After the Hawks scored five straight, the Pacers finished the quarter with an 8-0 run, capped by Jeff Foster' 3-pointer that made it 79-59.
Indiana was 10 of 19 from the field in the quarter, while Atlanta was 4 of 20.
Indiana pushed the lead to 24 points midway through the final quarter.
The Hawks' Jason Collins was ejected with 3.5 seconds remaining for a flagrant foul on Lou Amundson.
NOTES: Indiana won for just the second time in its last 11 games against the Hawks. ... Hawks guard Tracy McGrady was ruled out before the game because of back spasms. ... Hawks forward Al Horford strained his left shoulder battling under his own basket and was sidelined with 6:14 remaining in the first quarter.