Jaylen Brown and Jayson Tatum combined for 62 points and the Boston Celtics clamped down late to hold off the Atlanta Hawks in a 128-120 thriller on Thursday to win their NBA Eastern Conference first-round playoff series.

The Celtics, trying to get back to the NBA Finals after falling last season to the Golden State Warriors, won the best-of-seven series 4-2 to line up a conference semi-final showdown with a Philadelphia 76ers team led by Joel Embiid and James Harden.

Trae Young, hero of the Hawks' 119-117 come-from-behind victory in game five that extended the series on Tuesday, scored 30 points with 10 assists.

But Young ran out of gas in the second half, scoring just five points after the break and finishing the game nine-for-28 from the field.

Brown scored 32 points and Tatum had 30 for the Celtics, who used an 11-0 run in the fourth quarter to finally take control of a game that featured 22 lead changes and was tied 15 times.

"I think in that fourth quarter, four minutes left, we made winning plays," Tatum told broadcaster TNT. "We talked about it before the game -- do whatever it takes."

The lead changed hands seven times in the fourth quarter alone. Former Hawk Al Horford put the Celtics up for good with a three-pointer with 3:35 remaining.

Tatum followed with another three-pointer, Brown produced a block and Tatum slammed home a Horford miss to cap the 11-0 run that had the Celtics up by eight with 2:07 to play.

Atlanta wouldn't get the deficit below five points the rest of the way.

Marcus Smart scored 22 points, Malcolm Brogdon added 17 off the bench and Horford chipped in 10 for the Celtics.

"I thought Smart was tremendous, especially late in the fourth quarter," Celtics coach Joe Mazzulla said. "He got us organized and then he was kind of the triggerman. They were blitzing, he made the right plays."

Young, whose 38 points in game five included a game-winning three-pointer, said he just couldn't shake Smart in the second half.

"Marcus was being way more aggressive," Young said. "In the second half he was more just connected to me. They picked up the physicality. It was tough."

In the end, Hawks coach Quin Snyder said, the Celtics were just too much.

"Obviously Tatum and Brown were a handful, which we expect," Snyder said. "We blitzed their pick and roll, we hit them on the dribble, hit them on the pass and when we didn't they were able to make plays. When we did, you're susceptible to the three."

The Celtics made 18 of their 42 three-point attempts, Brown draining six from beyond the arc and every Boston starter making at least one trey.

Even so, Snyder said, "we were right there. It's a tough game."

Added Young: "You've just got to tip your cap sometimes and give credit where it's due."

The second-seeded Celtics, the highest seeds left in the East after the Miami Heat's upset of the top-seeded Milwaukee Bucks, host the third-seeded 76ers in game one on Monday.