The defending Eastern Conference champion Boston Celtics narrowly avoided the nightmare scenario: Game 7 against Trae Young and his seventh-seeded Atlanta Hawks after leading the first-round series, 3-1.

Late in the fourth quarter of a wild ride that featured 22 lead changes and 15 ties, the Celtics finally established their first cushion since the game's opening minutes, as mainstays Jayson Tatum, Jaylen Brown, Marcus Smart and Al Horford executed to perfection down the stretch of a 128-120 victory.

The rest was far from perfect, but the Celtics eliminated the Hawks in Game 6 to advance to the conference semifinals, where they will face the third-seeded Philadelphia 76ers. Game 1 is scheduled for Monday night.

"We didn't want to be the team going home with an L," said Brown, "so we just found a way to win."

Brown scored a team-high 32 points. Tatum added 30 points and team highs of 14 rebounds and seven assists. Game 6 marked the second time in the series — and in their playoff careers — that both scored 30 points in the same game. Including the regular season, Boston is now 23-1 when both eclipse 30 points.

Young's 30 points led the Hawks, who got double-digit scoring nights from five others, including De'Andre Hunter (20 points). Dejounte Murray, fresh off his Game 5 suspension, added 14 points and 11 assists.

After scoring 25 points in the first half, Young missed 12 of 13 shots in the second half.

Brown's 3-pointer over Murray with five minutes remaining in the fourth quarter forced the game's last tie, 113-113. Horford and Tatum followed with back-to-back 3-pointers, and Tatum's dunk of an errant Horford 3 pushed Boston's advantage to 121-113 with 2:07 left. Atlanta never drew within two possessions again.

"Just understanding it was time," Tatum said of what motivated the Celtics' effort in the last five minutes, when they blitzed the Hawks for 18 points on 6-of-9 shooting (4 for 6 from deep). "It was a back-and-forth game. They were hitting big shots; we were hitting big shots. We could feel it. Everybody was locked in, getting blocks, chasing down rebounds, hitting big shots. We've been in that situation before as a unit."

Down 126-120 with 19 seconds on the clock, the Hawks failed four times to inbound the ball. Unable to see over Smart, Young twice threw the ball off the Celtics guard and out of bounds to avoid spending Atlanta's final timeout. Hunter took over, threw his first attempt off Horford and tossed the second into the stands.

The sequence was a fitting end to a strange and entertaining Game 6.

Smart scored nine points in the game's first three and a half minutes, assisting on the Celtics' other five points on their way to an early 14-4 advantage. The Hawks could have begun their vacation then and there, but as has been the case all series, they never quit. The first of Young's four 3-pointers capped a 15-4 run and marked the first lead change of the game, giving Atlanta a 19-18 advantage midway through the first quarter.

From the 7:17 mark of the first quarter until Tatum's put-back dunk with two minutes left in the fourth, the score was within five points on either side for all but 18 seconds — remarkable, given both teams' offense.

"They had the utmost confidence throughout this game," added Tatum. "Man, you could see it. The way they played, the shots that they were hitting, the crowd was into it. That was a fun game to be a part of."

The Celtics logged 50/43/94 shooting splits as a team on the night, but the Hawks led 100-98 after three quarters, thanks to their 21 points on 11 offensive rebounds (eight from Clint Capela and Onyeka Okongwu) entering the final frame. Boston dialed up its defense in the fourth, holding the Hawks to 20 points — the first time either team scored fewer than 30 in any quarter. Young finished 0 for 7 from the field in the fourth.

The conference appeared to be breaking Boston's way earlier in the week, when injured Sixers star Joel Embiid was questionable for the start of the second round and the Miami Heat stunningly seized control of their first-round series against the top-seeded Milwaukee Bucks on the other side of the East bracket.

Except, the Celtics blew a 12-point lead in the final five minutes of Tuesday's Game 5, affording Embiid two extra days of rest, and for a while it looked like they may be headed for a Game 7 with Atlanta on Saturday.

Despite Thursday's close-out victory, Game 6 tested Boston's biggest fears against a Philadelphia team the Celtics have owned in the playoffs twice in the past five years. The Hawks' guards relentlessly attacked the 36-year-old Horford, their bigs pounded the glass against Boston's smaller lineups, first-year Celtics coach Joe Mazzulla is still searching for a consistent rotation, and his team lost focus for prolonged stretches.

"Not much different than this series," Mazzulla said of the Sixers. "They've got two All-Stars, a great bench and a great coach. I expect it to be really hard, and I expect our guys to just constantly stay in the fight."

Those are concerns for another day. The Celtics avoided their first-round nightmare. Barely.