ATLANTA — In many way, the defining moment of Joel Embiid’s career was when he cried in a Scotiabank Arena tunnel after losing to the Toronto Raptors in Game 7 of the 2019 Eastern Conference semifinals.

Back then, the 76ers center promised he’d come back better if given the opportunity.

His opportunity comes 8 p.m. Sunday when the Sixers face the Atlanta Hawks in a winner-take-all Game 7 conference semifinal at the Wells Fargo Center.

“I’m excited,” Embiid said. “This time around, it’s at home. Even back then, I believe that if we had home court, it would have been easier to win. But that’s why we worked so hard in the regular season to get that home-court advantage.”

The Sixers posted a conference-best, regular-season home record of 29-7 on their way to securing the East’s No. 1 seed. However, they’re just 1-2 at home in this series. Their last loss, Game 5, came after they blew a 26-point lead.

“That’s something we should had never done,” Embiid said.

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This series has defied the notion of home-court advantage, though. Two of the Sixers’ three series victories came at State Farm Arena. Embiid, however, thinks the way the Sixers remained locked in during their Game 6 victory will prepare them for the biggest game of the season.

“We just kept telling each other, you know, ‘We got to be focused for 48 minutes,’” Embiid. “So that’s what we had to do and we will be fine.”

This contest could be another defining moment for Embiid and the Sixers.

His first two postseason experiences, in 2018 and 2019, ended with second-round exits. And the Sixers were swept in the first round last season.

Those successive endings led to the Sixers making a head-coaching change and tweaking the front office, which led to hiring Daryl Morey as president of basketball operations. Now, they’re one win away from winning a second-round series for just the second time in the franchise’s last 11 appearances, dating back to 1986. They beat the Raptors in seven games in 2001 en route to finishing as NBA Finals runners-up.

“We have to be ready,” coach Doc Rivers said. “We have to be prepared. I tell them all the time when you feel prepared, you feel freedom. And the more they can prepare, the more free they can be on the floor. That’s what we are going to try to get to them before the game.”

The franchise is 6-10 all-time in Game 7s. However, they’re 5-1 at home. They have won their last four home Game 7s with their most recent coming in 2001, capping their second-round series with the Raptors.

Like any Game 7, there’s a lot at stake for the Sixers on Sunday’.

They know that anything short of reaching the conference finals would be considered a failure of a season.

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It doesn’t matter that they had the conference’s best regular-season record. Nor does it matter that Embiid was the league MVP runner-up, or Ben Simmons being runner-up for defensive payer of the year, or that Matisse Thybulle joined them both on the league All-Defense teams. (Simmons was first-team, while Thybulle and Embiid were second-teamers.)

Those things would be nothing more than a footnote if the Sixers lose Sunday night.

This season would be remembered for the Sixers blowing huge leads in Games 4 and 5 en route to being eliminated by the fifth-seeded Hawks. The list of critics saying the Sixers should trade Simmons will grow.

Embiid, Simmons, and Harris can recall the hurt they felt while losing to the Raptors in Game 7 two seasons ago.

Back then, Kawhi Leonard’s 15-foot fadeaway jumper at the buzzer lifted the Raptors to a 92-90 victory.

The All-Star small forward was originally guarded by Simmons until Embiid left Pascal Siakam and cut Simmons off. Leonard dribbled to the corner and fired up a shot over Embiid as time expired. His high-arcing shot hit the rim four times before dropping into the basket. Leonard was immediately mobbed in front of the Raptors bench.

Embiid began crying on the court after the first buzzer-beater in a Game 7 in league history. He had to be consoled by Raptors center Marc Gasol. Then he was seen crying in the tunnel.

“I don’t know, Game 7, losing the game that way,” Embiid said following the game of what was going through his mind. “Last shot after a hard-fought game. I feel like we had a chance.

“A lot of things go through your mind and it [stinks]. … I can’t explain it. It just [stinks].”

Will he feel that pain, again? Or will he and the Sixers finally get over the hump?