ATLANTA -- Despite Kevin Garnett's team-high 24 points and yet another Rajon Rondo triple-double, the Atlanta Hawks were able to storm back from a 27-point first-half deficit for a 123-111 double-overtime victory Friday night.

"[We] are a good team," a deflated Garnett said following the loss. "I thought we came out and played aggressive like we needed to. We had a chance to put [the Hawks] away, but we just didn't do that. When you have teams down, you have to step on them and finish the game."

The Celtics, who have missed that killer instinct thus far this season, followed another strong start with a miserable finish.

Boston crumbled midway through the second quarter, straying from the defensive tenacity and crisp ball movement that allowed it to build such a first-quarter lead, and instead made poor decisions on both ends of the court.

"I thought [the game] changed when we put the starters back in with about five minutes to go in the second quarter," coach Doc Rivers said. "Our bench got us up by 27 points, but then they cut into the lead before the half. I thought [when the Hawks cut the lead to 19] was a huge turning point because it gave them a belief."

Jeff Green, Jason Terry and Courtney Lee looked much more like the stud reserves they were expected to be upon signing in Boston over the first half of the game, combining for 26 points off the bench and high-energy plays the team had been lacking.

To open the second half, Hawks coach Larry Drew inserted Devin Harris in place of Ivan Johnson, finding an area to attack Rivers' reliance on sticking with his veterans. The move sparked a 21-2 Atlanta run that would eventually doom the Celtics.

For Rondo, though, it wasn't about Drew's move to speed up the game and get in transition. It was more about his team's defensive effort.

"The game shouldn't have gone to overtime," Rondo said. "Transition defense. Whether it was turnovers or bad shots, it was kind of a layup drill in the third quarter [for Atlanta], and then [Kyle] Korver got hot."

Korver would hit three 3-pointers in the third quarter, but he was vital to Atlanta's survival when Boston was pulling away in the fourth.

As the Celtics extended a 10-point lead with just four minutes to go, Korver knocked down two 3s in a two-minute span to bring Atlanta within two. Korver set a Hawks franchise record with eight 3s in the half.

Boston had a chance to win the game in regulation, but a missed floater from Rondo and a key defensive stop from Paul Pierce sent the game into overtime.

Pierce would eventually have a shot to win the game in overtime, but Josh Smith blocked a potential game winner from the elbow, sending the contest into another overtime.

With Garnett fouled out of the game in the second extra session and tired legs from their second night of a back-to-back, the Celtics just didn't have enough fight left to overcome a 10-0 second-overtime run that put them away for good.

"Never too high or never too low," Rondo commented on Boston's loss after the game.

For these Celtics, there isn't much lower they can go.