“We didn’t play well enough to deserve the win, and they did.”

Jayson Tatum says the Celtics let the Hawks get 'too comfortable' in upset loss
Jayson Tatum tweaked his ankle on Tuesday night. Danielle Parhizkaran/Globe Staff

The Celtics let go of their mid-game lead and ultimately fell to the Hawks 117-116 after a weak defensive performance Tuesday night.

The NBA Cup opener saw 20 turnovers and 20 offensive rebounds in Atlanta’s favor. Despite the absence of Hawks’ star point guard Trae Young, the Celtics continued to let them score during a messy second half.

“We just let them be too comfortable,” Jayson Tatum told reporters. “We didn’t play well enough to deserve the win, and they did.”

Though Boston was up 65-54 after the second quarter, they gave away several layups and “let go of the ropes” in the third quarter, Tatum said. Jaylen Brown also admitted they were too careless after expecting to win, and the team wasn’t as synced as they normally are. He and Tatum combined had 11 turnovers.

“They outplayed us,” coach Joe Mazzulla said. “We just didn’t connect on our passes, but it’s a credit to their physicality and their ball pressure.”

Tatum said he will play on Wednesday night against the Nets, though his ankle is still a “little tender” after pushing through the last two minutes against the Hawks.

“We got some stuff to clean up,” said Brown, referencing defense, physicality, rebounding and switching. “It’s a new season, it’s a new journey, and we’re looking forward to embracing those moments.”