Marcus Smart returned to the Celtics’ lineup Thursday night and was one rebound shy of a triple-double as Boston routed Miami in Game 2 of the Eastern Conference finals, 127-102. Lynne Sladky/Associated Press

MIAMI — Jayson Tatum scored 27 points, Marcus Smart and Jaylen Brown each had 24 and the Boston Celtics dominated the first half to roll past the Miami Heat, 127-102, on Thursday night, tying the Eastern Conference finals at a game apiece.

Smart was a rebound shy of a triple-double, adding 12 assists and nine rebounds.

Grant Williams scored 19 points for Boston, which used a 17-0 run late in the first quarter – fueled by five 3-pointers in the span of six possessions – to take control. Payton Pritchard and Al Horford each had 10 points for the Celtics.

Jimmy Butler scored 29 points in 32 minutes for Miami, which fell to 7-1 at home in these playoffs. Gabe Vincent and Victor Oladpio each scored 14 points, and Tyler Herro added 11.

The Celtics – now 4-0 in these playoffs in the game immediately following a loss – made 20 shots from 3-point range to Miami’s 10.

Game 3 is Saturday in Boston.

The margin could have been worse: Boston led by as many as 34 points in the fourth, putting this game on the cusp of really good Celtics history and really bad Heat history. The Celtics’ record for biggest postseason win is 40, the Heat record for biggest postseason loss is 36, and those numbers were within reach before a meaningless Miami run over the final moments.

Boston trailed by 10 in the first quarter, then outscored Miami 60-21 over the next 18 minutes – a 39-point turnaround that resulted in a 70-45 halftime lead.

The 25-point halftime lead was the biggest by the Celtics in any road playoff game, topping a 22-point edge at the break at Chicago in 2009.

Brown had 11 points in the first quarter, when the Celtics went 9 for 11 from 3-point range. Tatum then scored 17 points in the second and Boston kept pulling away, on a day where everything went the Celtics’ way. They learned earlier in the day that two starters – Horford (virus-related issues) and Smart (mid-foot sprain) – were cleared to play in Game 2 after missing the series opener.

“I got to get my rest, got to get my health back, got to watch and see some things and come out and execute in this game,” Smart said.

And the good news kept coming well into the night.

Butler did all he could to try and manufacture a comeback, scoring 16 points in the third quarter and getting the Heat within 17. But a 12-2 run late in the quarter by the Celtics restored a 27-point edge. The lead was 96-71 going into the fourth and the outcome was never remotely close to being in question the rest of the way.

Miami didn’t even use its starters in the fourth quarter.

TIP-INS

Celtics: Technically, Boston had one other “road” game with a bigger halftime lead. The Celtics were the designated visitor on Sept. 7, 2020 – in the bubble at Walt Disney World – when they led Toronto by 27 at the break. … With Horford back, Grant Williams returned to his off-the-bench role. … Tatum got his second foul with 4:14 left in the first, after charging into Butler. The entirety of the 17-0 run came with him on the bench.

Heat: Kyle Lowry (hamstring) sat for the eighth time in the last 10 games. … It was the first game since Dallas-Atlanta on Feb. 1, 2020, in which both teams had a 10-point lead in the first quarter. … P.J. Tucker scored Miami’s first five points, all in the game’s first 51 seconds. It was his 863rd career game, the first in which he had five points in the first minute. Those were his only points of the night, and he left in the third quarter because of a left knee contusion.

25 TWICE

This Boston team is the sixth club in the last 25 years to have two separate games where it led by at least 25 points in Miami in the same season. The Celtics also did it on Nov. 4. The other teams who pulled it off: Milwaukee last season (won NBA title), San Antonio in 2013-14 (won NBA title), Boston in 2007-08 (won NBA title), Toronto (2007-08) and Charlotte (2000-01).

500 AND COUNTING

The Heat announced their 500th consecutive sellout, excluding games affected by the pandemic. Only Dallas (867 and counting), Portland (814 from 1977 through 1995), Boston (662 from 1980 through 1995) and Chicago (610 from 1987 through 2000) have streaks that the NBA counts as being longer.