The zone did it.

The 76ers’ tough stretch against the Miami Heat’s 2-3 zone defense led to their first home defeat of the season. The Heat escaped with a 108-104 victory over the NBA’s last team with an unbeaten home record Wednesday night at the Wells Fargo Center.

The loss snapped the Sixers’ 15-game, regular-season home unbeaten streak dating back to last season. They had won the first 14 home games and the final home game of last game.

The Sixers fell to 20-9 after their second straight loss, following Sunday’s 109-89 road setback to the Brooklyn Nets.

Meanwhile, the Heat improved 20-8 while moving into third place in the Eastern Conference standings. The Sixers fell from second to fifth place.

Some will point to Al Horford’s missing what would have been a go-ahead, 29-foot three-pointer with 4.8 seconds left. The power forward missed the wide-open three with the Sixers trailing 106-104.

But Philly had been put in a hole because it had a tough time making outside shots against the zone, going 12-of-39 (30.8%) on three-pointers. The Sixers shot 38-for-90 (42.2%) overall. At times, they looked like a team that rarely practice against a zone.

“I think that we ended up overthinking it probably too much,” coach Brett Brown said. “I feel like we’ve been really quite good against a zone this year.”

He added that he thinks the Sixers have the NBA’s fifth-best offense against the zone.

“That’s what they tell me,” he said. “I feel like [the Heat’s 2-3 zone] put us on our heels. I don’t feel like we responded the way that I thought we would.”

Ben Simmons, 2nd from right< of the Sixers goes up for a shot against Bam Adebayo, center, of the Heat during the 2nd half at the Wells Fargo Center on Dec. 18, 2019.
CHARLES FOX / Staff Photographer
Ben Simmons, 2nd from right< of the Sixers goes up for a shot against Bam Adebayo, center, of the Heat during the 2nd half at the Wells Fargo Center on Dec. 18, 2019.

The Sixers really struggled against the zone in the second and third quarters before adjusting. They went 5-for-11 on three-pointers in the final quarter to help get them back into the game.

Miami rookie point guard Kendrick Nunn led all scorers with 26 points. Bam Adebayo added 23 points and nine rebounds.

Joel Embiid paced the Sixers with 22 points and a game-high 19 rebounds. Tobias Harris added 20 points.

The Sixers fans, once again, let the Heat’s Jimmy Butler have it. The former Sixer was booed during pregame introductions and every time he touched the ball. The boos turned into cheers whenever he missed a shot and made a mistake.

Some fans seem convinced that Butler orchestrated his sign-and-trade deal with Miami because he didn’t want to return to Philly. So, like in the teams’ Nov. 23 matchup in the same arena, they let him hear about it.

However, multiple sources have said the Sixers didn’t want him back. So if he indeed wanted to leave, the split was mutual. But he still heard the boos on a night he scored 14 points on 5-for-11 shooting, with four turnovers.

Heat coach Erik Spoelstra’s adjustment to the zone enabled his squad to get back into the game in the second quarter. The Sixers weren’t exactly surprised by his tactic.

“It was on the scouting report,” said Embiid, who only had three second-quarter shot attempts. "I felt like we weren’t aggressive enough in the first half. I don’t remember myself being in the action or getting the ball.

“We knew they were going to do it at that point, but I guess we didn’t act on what we talked about.”

Philly had built commanding 12-point cushion (41-29) with 7 minutes, 28 seconds left in the half. However, Miami closed out the half with a 27-7 run to take a 56-48 lead. The Heat scored 37 points in the second quarter on 65% shooting (13-for-20). Meanwhile, the Sixers scored just 19 points and made just 7 of 23 - mostly wide open - shots for 30.4%.

“When you don’t make shots and they are playing zone, they are going to keep doing it," Embiid said. “That is how they won the game.”

The Heat, however, returned to man-to-man at the start of the second half before quickly going back to zone. The teams played even in the third quarter, as Miami took an 82-74 cushion into the fourth quarter. In addition to being a zone defense, the Heat made 9 of 16 three-pointers after intermission.

Miami opened the fourth quarter with a Duncan Robinson three-pointer and Tyler Herro layup, forcing Brown to call a timeout 45 seconds in. The Sixers received loud boos at the start of the timeout while trailing 87-74.

The boos got louder after the Heat took a 96-80 advantage with Chester native Derrick Jones’s dunk with 7:52 to play.

Derrick Jones, left, of the Heat dunks over Joel Embiid during the 2nd half at the Wells Fargo Center on Dec. 18, 2019.
CHARLES FOX / Staff Photographer
Derrick Jones, left, of the Heat dunks over Joel Embiid during the 2nd half at the Wells Fargo Center on Dec. 18, 2019.

But the Heat let the Sixers back in the game with several bad shots. Philly pulled within eight points (99-91) after Josh Richardson’s three-pointer at the 3:36 mark. Then another three-pointer by Richardson closed the gap to 101-97 with 2:13 to play. But Jones drained a three to push the Heat’s lead back up to seven (104-97) with 1:07 left.

After Embiid made a layup with 51.8 seconds left, Ben Simmons stole the inbounds pass. The point guard passed the ball to Embiid, who scored with 47.9 seconds remaining to close the gap to 104-101.

Butler made a pair of foul shots on the ensuing possession. Harris responded with a three-pointer at the other end to pull the Sixers within two points at 106-104.

The Sixers had a chance to win the game after Nunn (game-high 26 points) missed a pair of foul shots with 12.7 seconds left. But Horford missed a three-point attempt with 4.8 seconds remaining. The Heat went on to win by four after Adebayo’s foul shots at 1.5 seconds left.

“I’m not unhappy with that,” Brown said of Horford’s shot. “I give Miami credit. They crowded the paint. Ben’s a missile, playing downhill. He kicked it out and, you know, a two would have been good, a three would have won it. So I don’t mind a lick.”

Goran Dragic (strained right groin), Dion Waiters (team suspension), Justise Winslow (lower-back strain), and James Johnson (personal reasons) were all out for the Heat.