Atlanta trailed 39-28 after one quarter, but held New York to 38 points in the second half of its second straight win.
''For our guys to make a stand defensively was great to see,'' Hawks coach Lloyd Pierce said.
New York also blew a halftime lead in Monday's 128-110 loss to Phoenix.
''For whatever reason, we are hitting the wall in that third quarter,'' Knicks coach David Fizdale said. ''That's our new quarter for some reason. We look fatigued and we stop moving the ball. Everything that was sharp in the first half, kind of fades out in the second. We have to figure it out.''
Mudiay's layup gave New York a 99-95 lead with 7:23 left, but Atlanta responded with a 9-0 run. Young capped the decisive stretch with a layup with 3:47 left.
After Mudiay hit a jumper for the Knicks, Young converted a three-point play to extend the Hawks' lead to 107-101 with 3:04 remaining.
''These teams are desperate to get wins just like we're desperate to get wins,'' Knox said. ''You could just tell in that second half they came out to try and win the game and we come out a little sluggish. They come out with a certain type of energy that we just don't respond to.''
The Knicks opened a 46-31 lead on Luke Kornet's 3-pointer with 9:35 left in the second quarter. Huerter's driving layup trimmed Atlanta's deficit to 69-60 at halftime.
''Coach was definitely getting into us (at halftime),'' Young said. ''That's not who we are. That's not how we want to be represented. We want to be a team that comes out and competes on both ends. We didn't make it tough for them in the first half.''
Hawks: Vince Carter, the NBA's oldest active player at 41, was scoreless in 13 minutes, but he grabbed six rebounds. ... The Hawks lead the all-time series with the Knicks 196-177, but are only 65-94 on the road against New York.
Knicks: Rookies Allonzo Trier (strained left hamstring) and Mitchell Robinson (sprained left ankle) remain sidelined by injuries.
New York forward Kristaps Porzingis, who is coming back from left knee surgery, has made good progress in his rehabilitation, according to the team. He is expected to be re-evaluated in mid-February.
YOUTH IS SERVED
Young is the only Atlanta player to start each of the team's 31 games this season.
Hawks: Visit Detroit on Sunday.
Knicks: Host Milwaukee on Tuesday.
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