Joe Mazzulla clapped on the sidelines as his Boston Celtics stars Jayson Tatum and Jaylen Brown scuffled against the Atlanta Hawks. Mazzulla refused to step in as Tatum got tangled with Onyeka Okongwu.

The Atlanta Hawks have made a change in their starting lineup over the past few games, starting Onyeka Okongwu over Clint Capela.

The Celtics blew a 3-point lead late before eventually losing in a heated overtime period to the Atlanta Hawks.

There is no fear,” coach Joe Mazzulla said. “I'm actually more excited at this juncture of the season than I was at the beginning.”

Some tempers flared early in overtime between the Celtics and Hawks, though there were no extra fouls or techs afterwards.

The Celtics snatched defeat from the jaws of victory Saturday night, making mental errors that allowed the Hawks to steal a win in Boston.

Celtics’ star Jayson Tatum added 23 points after coming into the game listed as questionable with a left shoulder strain. He shot 7 of 21 overall.

Trae Young tied it late in regulation with two free throws; finished with 28 points to hand Boston another puzzling loss.

Onyeka Okongwu has recorded three consecutive double-doubles off the bench, and made history for the Hawks doing so.

Dyson Daniels hit a short jumper in the lane with just over a minute left in overtime and Onyeka Okongwu made two free throws with 11 seconds left, lifting the Atlanta Hawks to a 119-115 victory over the Boston Celtics on Saturday night.

Dyson Daniels hit a short jumper in the lane with just over a minute left in overtime and Onyeka Okongwu made ... and Daniels finished with 23 points. Jaylen Brown had 24 points, 11 rebounds ...

As Jayson Tatum and Onyeka Okongwu wrestled for the ball, Celtics coach Joe Mazzulla was watching from the sidelines with his thumbs in the air, likely signaling for the officials to call a jump ball.