But Maxey zipped past Pritchard and found a clear lane to the basket, where he put in an off-balance layup just before time expired. The play all but finished off the Celtics in this 118-114 loss, and it was an example of the uncharacteristic missteps that doomed them.

As a dangerous January schedule looms, Boston hasn't been playing up to its standard recently, falling 4 games out of first in the East.

What to KnowThe Celtics have lost back-to-back games for the first time all season.Jayson Tatum was the Celtics' best player with 32 points and 15 rebounds.Caleb Martin scored a season-high 23 points and hit 7-of-9 attempts from 3-point range.Tyrese Maxey led the Sixers with 32 points and 12 assists. The Celtics will be back in action against the Pacers on Friday and Sunday at TD Garden. The Boston Celtics' defense let them down in their Christmas Day loss to the Philadelphia 76ers at TD Garden. This game was tied 82-82 after three quarters, and then the Sixers opened the fourth quarter with an 18-4 run. The Celtics were able to trim that lead to three points with 2:27 remaining, but they couldn't finish the comeback as Philly escaped with a 118-114 victory. Check out our live blog below for a complete recap of the game.