The Raptors trailed 81-80 after Anderson's 3-pointer with 9:11 left, but Horford scored six of the next eight points, four on jump shots and two on a dunk, putting the Hawks up 89-80 with 7:26 to play.
Teague made back-to-back 3-pointers then added a driving jump shot, giving the Hawks a 97-80 lead with 4:39 left.
DeRozan snapped Toronto's 4:48 scoreless streak with a pair of free throws, but Horford answered with a slam off an alley-oop from Teague.
Gay scored six in the first and DeRozan and Amir Johnson each had five as the Raptors led 25-20 after one.
Ross scored nine points in the second and DeRozan had seven, including a jump shot with less than two seconds left, giving the Raptors a 54-44 lead at the half.
Atlanta took a 71-69 lead, its first since early in the second quarter, on Smith's 3 with 3:23 left in the third. Ross scored four of Toronto's next six points as the Raptors reclaimed the lead, but a pair of free throws by Smith with 30 seconds left knotted the score at 75-all heading to the fourth.
Atlanta's Kyle Korver extended his streak of game with at least one 3-pointer to 65. Korver's streak is the fifth-longest in NBA history. Reggie Miller (68 games) had the fourth-longest, while Dana Barros tops the list with an 89-game streak.
NOTES: Hawks G Devin Harris missed his second straight game with a sore left foot. ... Toronto rookie F Quincy Acy was not available because of a sore hamstring. ... Toronto shot 5 for 20 in the fourth quarter. ... The Raptors made 20 turnovers, leading to 24 points for the Hawks.