I like the Celtics in this spot even if Jayson Tatum remains out due to COVID-19 protocols. It's a nice bonus if he's able to play.
This is a monster rivalry. So my inclination is to grab the points. That's especially so in the case of the Celtics, who are 22-7 ATS the past 29 times as underdogs.
Boston is this big of a 'dog because the 76ers are home and just defeated the Celtics, 117-109, this past Wednesday. The 76ers made 36 of 45 free throws in that game. Boston was 13 of 20 from the foul line. The Celtics were not happy with that free throw disparity. Joel Embiid shot more free throws than Boston did as a team. 
Embiid had a monster performance with 42 points and 10 rebounds. He's a great player. But the Celtics have the center depth and astute coaching of Brad Stevens to make adjustments. 
One bright spot for Boston in the loss to the 76ers was Kemba Walker looking good in his second game back from a knee injury. He scored 19 points and had good leg movement.