While attempting to contain Hawks guard Trae Young on the perimeter, Hayward turned right into a hard pick set by 6-foot-10 John Collins, driving his head directly into the big man's left shoulder.
The Celtics must now face a Hawks squad that arrives in Boston riding a two-game SU win streak.
The C's have won four of their last five games and they're just two games behind the Sixers for the No. 4 seed in the Eastern Conference.
In their last matchup on January 19, Boston won 113-105 as Kyrie Irving led the Celtics with 32 points and five assists.
Irving fell just short of his second straight triple-double with 11 rebounds and nine assists along with his 30 points.
Marcus Morris had 19 points and Jayson Tatum 18 for Boston, which has won six of eight. In the second, the offensive output quieted down a little or both sides.
Boston's lead swelled to 25 in the 3rd, but a 28-6 run by the young Hawks cut it to a 3-point game with 7 minutes to play. Also, Al Horford dealt with a sore knee as well during the game.
But Boston still led the way and extended their lead to 12 points, 74-62, at the half. I'm sure he does. He went to the locker room for further evaluation, and the team later described his injury as a "strained neck" that kept him out of the remainder of the game. A few Celtics players became sick when they returned from their West Coast trip earlier this week.
As much as they've been trying to rally lately, the Atlanta Hawks will likely be the next team eliminated from playoff contention, but that will likely have zero effect on how Atlanta plays on the road today against the Boston Celtics.
Boston's season high for any quarter is 45 points against the Hawks in Atlanta on November 23. Reserve center Daniel Theis and backup point guard Terry Rozier missed Thursday's win over the Sacramento because of illness, but they played Saturday. The Celtics had 43 in the first Saturday.
SUNS 138, PELICANS 136: Josh Jackson hit a tying 3-pointer with 2 seconds left in overtime, the Pelicans were assessed a technical foul when they called a timeout they didn't have and Devin Booker hit the free throw to give Phoenix the lead for good in New Orleans.
"It's going to be a dogfight no matter who we're playing against", Irving said.