MIAMI — The 76ers keep saying everything will be fine.

Even when they were decimated by a COVID-19 outbreak and injuries, the Sixers had one message: “For us, it’s the next man up mentality and being locked in on the game plan.”

They said it confidently, and we’re about to find out if it’s true when the stakes are high.

The Eastern Conference’s fourth-seeded Sixers face the top-seeded Miami Heat in the second round of the playoffs. Game 1 of the best-of-seven series is set for 7:30 p.m. Monday at the FTX Arena.

» READ MORE: Kyle Lowry out for Game 1 of Eastern Conference semifinals; optimism that Joel Embiid could return for either Game 3 or 4

The Sixers are heavy underdogs despite tying the season series at 2-2. That’s because they’re without MVP finalist Joel Embiid, who suffered an orbital fracture near his left eye and a mild concussion in Thursday’s first-round closeout game against the Toronto Raptors. The Sixers are going to replace him with a center by committee and what they call a James-dominant offense for guard James Harden.

“We’re coming into this, we haven’t changed our goals or our thoughts at all,” coach Doc Rivers said. “We’re going to be ready to play.”

Harden has the resume to be thrust into this role.

The point guard is a three-time scoring champion and the 2018 league MVP during his time as with the Houston Rockets. Harden is also third on the NBA all-time three-point list with 2,593. And the perennial All-NBA selection will go down as one of the great isolation players.

But Harden has appeared a step slow while overcoming a left hamstring strain this season And he’s shooting career lows of 41.0% from the field and 33.0% on three-pointers in 65 combined games this season with the Brooklyn Nets and Sixers.

» READ MORE: The Sixers were in a bind with Joel Embiid. His injury makes their trajectory more unclear than ever

That leaves the question: Can a Harden-based offense make up for the loss of Embiid for at least the first two games of the series?

The star center didn’t fly with the Sixers to Miami on Sunday. The series comes to the Wells Fargo Center for Games 3 and 4 on Friday and Sunday.

Prior to his injury, the Sixers centered their offense around Embiid. They spent the past couple days working on ways to highlight Harden’s strengths. “Be more aggressive,” Harden said of what a James-dominant offense looks like. “That’s what I’ve been doing [in the past]. I’ve been comfortable and used to that role for a long time.

“So just take what the defense gives me, being aggressive and making the right decision once I get to that point. More floor spacing. More attacks to the basket. And we just got to play free with the ultimate confidence as a group.”

But the Heat will look to take Harden out of his game just like they did to Trae Young in their opening-round series. The Atlanta Hawks’ All-Star point guard averaged 28.4 points on a career-best 46.0% shooting this season. However, the fourth-year player was limited to 15.4 points and 31.9% shooting in the opening round.

“They can do whatever they want,” Rivers said. “We’ll be ready. Really, that’s how I feel.”

With no Embiid, the Sixers expect Miami to trap Harden and shooting guard Tyrese Maxey.

“They’re going to try to bump them and all of that fake tough stuff,” Rivers said. “I always laugh at all that toughness stuff. You’re on a basketball court. … if you know what I mean.

“But you know, we will be ready for all that.”

» READ MORE: Sixers coach Doc Rivers defends decision to have Joel Embiid in late during a blowout

The Heat are also dealing with injuries with Cardinal Dougherty and Villanova product Kyle Lowry remaining sidelined with a left hamstring strain. Jimmy Butler (right knee inflammation), Tyler Herro (respiratory illness), Caleb Martin (left ankle sprain), Prep Charter product Markieff Morris (respiratory illness), Max Strus (right hamstring strain), and P.J. Tucker (right calf) are listed as questionable.

Regardless of who plays, the Sixers think they’ll be fine by paying attention to detail and limiting bonus possessions.

“Everything they do, they got to work for it,” Harden said. “They got to go through our bodies. Easy post up in transition, mishaps whatever that may be, open shots for their shooters. If we can limit those and take away those things as much as possible, we got a really good chance.”

Tobias Harris, who had a solid series against the Raptors, could be key on both ends of the floor for the Sixers. The team is also fortunate to have Matisse Thybulle, its best perimeter defender, eligible to play in every game in the series game. Due to being unvaccinated, he was ineligible to travel to Canada in the first-round series.

But early on, Harden’s play on offense could be the deciding factor in the series.

This will be a different role for him with the Sixers, but one he’s thrived in during his career.

“At this point, man, it’s a sacrifice to win games. I’ve been scoring. When I scored 30-something and lose, people are saying something. When I score 19 and we win, they are saying something. So at this point, I just do whatever it takes to win the game. I’m sacrificing. I’m the ultimate team player.

“So now, Joel’s out. I got to be more aggressive and score the basketball, get to the basket, and make the right decision. It’s no different than what I’m used to.”