BOSTON -- As the fourth quarter started Tuesday night inside TD Garden, it appeared the Boston Celtics were about to punch their tickets into the next playoff round.

But 12 game minutes later, those tickets remained unpunched.

"We had a tremendous opportunity," Celtics star Jaylen Brown said about trying to close out his team's first-round series in Tuesday's Game 5. "We controlled the game for the most part, and then Trae Young just put on a hell of a performance in the fourth quarter."

After Boston led the visiting Atlanta Hawks by as many as 13 points early in the fourth quarter, Young, Atlanta's clutch-performing point guard, took over. He scored the Hawks' last 14 points, including the game-winning 30-foot dagger over Brown with 2.1 seconds remaining in the 119-117 victory.

Asked if Boston let its collective foot off the gas after holding such a large lead in the final period, Brown admitted it may have.

"I guess you could say that," Brown said. "We made some bonehead plays, some fouls. We gave them some opportunities to get going. We've just got to finish the game.

"We let the game get away from us a little bit, and they just hit shot after shot down the line. When you give a team life, you give them a chance, and that's what we did."

Young's made basket allowed a seemingly overmatched Hawks team, which was playing without suspended All-Star Dejounte Murray, to force a Game 6 on Thursday night back in Atlanta. With his one-game suspension now complete, Murray will rejoin the team for the remainder of the series.

"I FaceTimed him as soon as I got in the locker room," Young said. "I told him 'Be ready.' I told him before the game that we were going to take care of business so he can play in Atlanta."

Murray had been suspended for the game after making contact with an official in Sunday's Game 4. It was largely because of Murray's absence that led to the Celtics entering the game as a 12.5-point favorite, making for the largest spread in any playoff game this postseason.

"We didn't talk about that. We've been focused on ourselves," Hawks coach Quin Snyder said about being declared pregame underdogs. "If we find things externally to be our source of motivation, I don't think you can win. So I understand it. People are making rational choices, but that doesn't mean we have to listen to them. We just have to compete, we just have to play."

Hours before Game 5, Murray told reporters at Atlanta's shootaround "a lot" led up to the incident involving him and referee Gediminas Petraitis. Some of it included a history of feeling disrespected by the official in the years before Murray was traded to the Hawks, Murray said.

"At the end of the day, I feel like, I don't think I should have been suspended," Murray said. "(But) I'm a grown man, and I hold my own and I take full responsibility for not being able to play for my teammates, and the fans and just the organization as a whole."

Atlanta's win spoiled what had been a strong offensive performance from Brown. He had a team-high 35 points, and was outpaced only by Young, who had 38. It's the fourth time in Brown's postseason career that the Celtics lost a game in which he scored 34 or more points.

When the night began, Brown -- back in the black mask he's been wearing to protect a healing cheekbone -- looked unstoppable, opening the game 5-for-5 from the field in an early stretch that included a step-back 3.

Brown's performance came after a 31-point showing in Game 4. All but two of those points came after Brown took off the mask he's been wearing since suffering a facial fracture in a Feb. 8 game against the Philadelphia 76ers.

"Maybe it was all in my head," Brown said after Game 4, "but I just needed a different look."

Fellow Celtics All-Star Jayson Tatum added 19 points Tuesday, many of which came in the second half. He struggled mightily offensively in the first half, going 1-for-5 from the field in the first quarter. Tatum missed his first five 3s, too, before breaking the drought 15 seconds into the second half.

"They're a really talented team, a well-coached team," Tatum said of the Hawks. "And they've got a lot of pride. So I knew it wasn't going to be easy."

Added Brown, an Atlanta-area native who had hoped to avoid another in-season trip home: "Only thing you can say is to get ready for the next one."

The winner of this series advances to the Eastern Conference Semifinals, with a matchup against the 76ers that begins Monday.