A HEAVY DOSE of déjà vu had hit the City of Brotherly Love.

The Philadelphia 76ers, having already blown a 16-point lead at home to the Boston Celtics in Game 4 of their Eastern Conference semifinal series, watched as Malcolm Brogdon's 3-pointer extended the Celtics' edge to five points with 2:04 remaining in the fourth quarter.

Trailing 2-1 in the best-of-seven showdown, the 76ers looked destined for another heartbreaking loss in a recent playoff history littered with them.

But James Harden, who had rediscovered his Game 1 form, kept scoring. P.J. Tucker willed in an and-1 off an offensive rebound with just over one minute remaining in the fourth. The 76ers fought back from the 105-100 deficit, forcing overtime, where Harden's corner 3 with 19 seconds remaining secured Philadelphia's win and tied the series at 2-2.

"We've just got veteran presence," 76ers center and 2023 Most Valuable Player Joel Embiid told ESPN. "Guys that know how to win, that know how to play.

"A lot of teams could have quit. But we just stuck together. We just got a different mindset this year."

Embiid would know. Past Sixers teams weren't defined by their ability to fight through adversity. In 2021, three late-game meltdowns -- most notably Ben Simmons passing up an open dunk in the closing moments of Game 7 -- cost Philly its East semifinal series against the Atlanta Hawks. Last season, the Sixers were suffocated by the Miami Heat defense in Games 5 and 6 after winning two straight to tie that East semifinal series.

Now, as Philadelphia faces rival Boston in Game 5 on Tuesday (7:30 p.m. ET, TNT), the Sixers head into the biggest game of their season believing this time will be different.

"Just our overall mental toughness has grown," 76ers coach Doc Rivers told ESPN ahead of the series against Boston. "We have grown up.

"Last year, when we went bad, if Joel didn't play well or James didn't play well, we were done. That's not true now. Tyrese [Maxey] can win a game for us. Tobias [Harris] can go off. And no one waits for anybody anymore.

"Now, no. F--- it. They just keep playing."

AFTER PHILADELPHIA FELL to the Heat on their home court in last year's playoffs, Embiid declared the 76ers needed something extra if they wanted to make a playoff run.

Specifically, he cited the player who had just helped the Heat beat him.

"Since I've been here, I'd be lying if I said that we've had those types of guys," Embiid said after that Game 6 defeat. "Nothing against what we have. It's just the truth.

"We never had [Heat forward] P.J. Tucker."

Fast forward to Sunday in Philadelphia, almost a year later with Tucker now a Sixer.

Tucker -- who finished Game 4 with six points -- somehow scooped up an air ball by Harris and rose for an and-1 layup that put Philadelphia in position to tie the score with a minute remaining in regulation.

But before Tucker went to the free throw line, he marched toward the NBA's newly minted MVP and gave him an earful. "When he's aggressive and assertive, it's impossible [to guard him]. And I seen him two, three plays in a row not do that. And we can't have it." Tucker said of the conversation he and Embiid shared.

"P.J. is a big part of [the team's increased resiliency]," Embiid told ESPN. "Getting on everybody else, getting on me, always reminding each of us, 'It's time to go. Stick together.'"

Tucker isn't alone. De'Anthony Melton, who arrived via a draft-night trade with the Memphis Grizzlies, has provided a similar level of toughness and grit, and several 76ers players and staffers also credit him with helping change the team's approach. Backup center Paul Reed's ability to settle into a role behind Embiid has helped, too.

But Tucker, who rarely scores but impacts winning in ways rarely seen on a box score -- is the face of the 76ers' new mentality.

"We're a team that doesn't give up," Tucker told ESPN. "You got to have [that mindset] to be a championship-caliber team. ... No matter how much somebody is up, they're always worried about you coming back. I love that. That's what you want to have a team say about you."

After Philly's Game 4 thriller, however, Rivers summed it up rather succinctly.

"The biggest difference? There's a guy named P.J. Tucker on our team now."

GEORGES NIANG KNEW there was something different about this year's 76ers team well before their Game 4 triumph.

Instead, it was during an innocuous road trip in mid-March, when the 76ers found themselves trailing the Cleveland Cavaliers by 13 points early in the third quarter in the first game of a three-game road trip, forcing Rivers to call a timeout.

"Last year, we would have been like, 'You know, f--- it,'" Niang, the veteran 76ers forward, told ESPN after Philadelphia's first-round sweep of the Brooklyn Nets. "'First night of a road trip, we'll get the next one.'"

"[But after the timeout] we ended up going on like a 7-0 run. Got it down to five and ended up winning that game and sweeping that whole road trip. That's when I was like, 'Damn, we really kind of turned the corner."

In 2020-21, the 76ers were 1-14 in games they trailed by 15 or more. They then held leads of 18 points in Game 4 and 26 points in Game 5 in what became a stunning seven-game loss to the Hawks. Philadelphia had four comebacks from down 15 or more last season.

"When s--- got hard last year," Niang said, "you could feel it."

This season has been a breakthrough: an NBA-leading eight comebacks from down 15 or more. In moments that previously seemed like end-all blows to Philadelphia's chances, instead the Sixers showed a different level of resolve.

That has been on display all series against the Celtics. With Embiid out for Game 1 because of a sprained LCL in his right knee, Harden poured in 45 points as the 76ers, who were 10-point underdogs according to Caesars Sportsbook, opened the series with a shocking victory.

After losses in Games 2 and 3, the 76ers controlled most of Game 4 before succumbing to Boston's second-half comeback. Philadelphia found a way to avoid a devastating -- and near season-ending -- loss.

As a result, the 76ers enter Game 5 with momentum -- and with the benefit of knowing they can take a punch and keep fighting back.

"We've done it all year," Rivers said. "This team is tough.

"Doesn't guarantee wins. Doesn't guarantee anything. But we're not going to go away."