Game 5 curse? Not for these Celtics.

Boston demolished the shorthanded and overmatched Miami Heat 118-84 on Wednesday night at TD Garden to advance to the second round of the NBA playoffs.

The Garden’s two tenants had lost five of their previous six home Game 5s — including the Bruins’ series-extending overtime loss against Toronto one night earlier — but the top-seeded Celtics left no doubt in this one, leading by 18 points after one quarter and as many as 37 in the second half.

Derrick White, fresh off a 38-point eruption in Game 4, scored 25 points, grabbed five rebounds and went 5-for-10 from 3-point range. Jaylen Brown finished with 25 and six boards. Jayson Tatum notched a 16-point, 12-rebound double-double and was a game-best plus-35.

“I really liked the intentionality we played with on both ends,” Celtics coach Joe Mazzulla said.

The Celtics’ second-round opponent will be either the Cleveland Cavaliers, the No. 4 seed, or the fifth-seeded Orlando Magic. The Cavs lead that series 3-2, with Game 6 set for Friday night in Orlando.

The Celtics cruised to victory Wednesday without starting center Kristaps Porzingis, who sat out after suffering a right soleus strain in Game 4. The calf injury is expected to sideline Porzingis through the second round, according to a pregame report from TNT’s Chris B. Haynes, with Boston hoping to get the standout big man back for the Eastern Conference Finals if it advances.

Veteran big Al Horford started in Porzingis’ place and played 23 minutes, finishing with eight points, six rebounds, three assists and one steal. Luke Kornet backed up the 37-year-old and played a playoff-high 18 minutes off the bench.

“Al always kind of sets the temperature for us,” Mazzulla said. “Just with his ability to impact the game basketball-wise, but also with his personality and his aggressiveness. He set the table for us, he set the tone for us, and everyone just followed suit.”

Whether the Celtics — who went 21-4 in games Porzingis missed during the regular season — can remain dominant without their 7-foot-2 unicorn will be the biggest question facing this team until his return.

The Celtics’ offense flowed through White and Brown early in Game 5, with the duo combining to score their team’s first 15 points. Most of those came on shots from the paint, including a driving Brown layup off an acrobatic loose-ball save by Jrue Holiday and a wide-open White dunk.

White also stayed hot from 3-point range, going 3-for-4 on triples as part of a 15-point first quarter.

Callahan: Celtics vanquish depleted Heat, playoff ghosts in Game 5 series clincher

Absent from that early scoring blitz? Tatum.

Boston’s best player didn’t attempt a field goal until eight minutes into the game and didn’t make one until the 1:40 mark of the first quarter — then proceeded to drill 3-pointers on back-to-back possessions. Sam Hauser (17 points off the bench) also sank two threes in the final minutes of a lopsided first quarter. The Celtics took a 41-23 lead into the second and never relented.

Up 31 with nine minutes remaining, Mazzulla began emptying his bench, giving players like Xavier Tillman, Svi Mykhailiuk and Jaden Springer their first extended run of the playoffs.

The Celtics out-rebounded the Heat 55-29, outscored them by 39 on 3-point shots and held them below 90 points for the third consecutive game, emphatically eliminating the team that upset them in last year’s East finals.

“I don’t really worry about what happened last year,” Mazzulla said. “At the end of the day, I liked the way we approached the series, regardless of who we were playing. It had an intentionality to it, it had an attention to detail and it had consistent physicality. That’s the most important thing.”

This was the fourth Celtics-Heat series of the last five postseasons, and the first of those that didn’t last six or seven games. All five of Boston’s wins came by 14 or more points.

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The Heat posted one comfortable victory — 111-101 on the road in Game 2 — but couldn’t withstand a tsunami of injuries to key players. Starters Jimmy Butler and Terry Rozier did not play in the series, and promising rookie Jaime Jaquez Jr. was unavailable for Wednesday’s finale.

After setting a franchise playoff record with 23 made threes in their lone win, the Heat went 9-for-28, 9-for-33 and 3-for-29 from deep in the final three games. They were 0-for-16 in Wednesday’s second half.

Bam Adebayo led Miami with 23 points and six rebounds. Tyler Herro had 15 points and was 1-for-8 from three.

Mazzulla called a timeout with less than a minute remaining, giving the crowd an opportunity to salute retiring play-by-play announcer Mike Gorman, who called his final game Wednesday after 43 years as the voice of the Celtics.

If Cleveland closes out its first-round series Friday night, Game 1 of the second round would be Sunday at 1 p.m. at TD Garden. If Orlando forces a Game 7, Boston’s next series would begin next Tuesday night at the Garden.

The Celtics went 2-1 against both teams during the regular season, winning all four matchups at TD Garden and losing their lone visits to Cleveland and Orlando.

“Wake up tomorrow, you’ve got to do it all over again against another team,” Mazzulla said.

Jrue Holiday of the Boston Celtics falls into fans during the first half of Game 5. The Celtics romped to eliminate the Heat. (Matt Stone/Boston Herald)