KISSIMMEE, Fla. – The 76ers kept telling us everything would be fine.

Even when they underachieved and had chemistry problems, the Sixers reminded us that it was just the regular season. Players, coach Brett Brown, and general manager Elton Brand had one message: “We are built for the playoffs.”

They said it confidently, and we’re about to find out if it’s true.

The Eastern Conference’s sixth-seeded Sixers (43-30) face the third-seeded Boston Celtics in the first round of the playoffs. Game 1 of the best-of- seven series is set for 6:30 p.m. Monday at the Field House on the Walt Disney World sports campus.

The Sixers are heavy underdogs despite having had a 3-1 advantage in the regular season,

They’re without their best defender is two-time All-Star Ben Simmons, who had his left knee scoped in Philadelphia on Monday. Their new starting lineup of Tobias Harris, Al Horford, Joel Embiid, Josh RIchardson, and Shake Milton hasn’t had a lot of time to build on-court chemistry in the NBA bubble. And Embiid banged up his right hand Wednesday.

“We clearly need a healthy Joel Embiid,” Brown said. “Nobody denies that. We can’t dismiss that. You need a healthy Joel Embiid to make the run that we need to make.”

But if he’s healthy, the coach believes the team can make a deep run for a couple of reasons.

He thinks the Sixers are starting to understand how to play with one another defensively.

“I feel like offensively, there is a path,” Brown said. “It’s a different path than it used to be with Ben, but there is a path.

“And I think that our scoring opportunities and our symmetry has been pretty clean and clear since the loss of Ben.”

The absence of Simmons does open up more scoring opportunities for Harris, Richardson, and Horford. Embiid and Horford did coexist better against the Orlando Magic on Aug. 7, the first game after Simmons’ injury.

However, it’s too early to give an accurate post-Simmons grade because the core players had limited minutes together in three of their final four seeding games.

Embiid was on the floor for just 5 minutes, 42 seconds against the Portland Trail Blazers on Aug. 9 because of a twisted left ankle. Two nights later, he, Harris, Richardson, and Horford sat out against the Phoenix Suns.

Then Embiid struggled passing out of the post in 13:35 of action -- all in the first half -- against the Toronto Raptors on Wednesday. That’s when he had X-rays on his right hand at intermission after having it whacked twice.

Still, Brown is outwardly optimistic and said he looked forward to playing the Celtics in the first round.

“We’ve been beaten up and now is our moment,” he said. “Now is our time to be recognized, and I think this group has the ability to do that as it sits.”

The Sixers speak of being built for the playoffs, but are they built for the Celtics?

Like Brown said, Embiid is going to have be healthy and play at an MVP level for them to have postseason success. And unlike in the previous two playoff openers, the Sixers head into Monday as huge underdogs.

One can argue that Boston is better than Philly, even with Simmons, based on how the Sixers struggled with him in their first three seeding games. The expectation is that they don’t have the proper pieces to defeat the balanced and athletic Celtics in a seven-game series.

The Sixers re-signed Harris to a five-year, $180 million deal. They also gave Horford a guaranteed four-year, $97 million contract. They gave Simmons a five-year extension for around $170 million.

They also parted ways with three pieces in Jimmy Butler, JJ Redick, and T.J. McConnell whom they could desperately use against Boston.

Playoff basketball is all about having a closer (Butler), a lethal sharpshooter (Redick), and a pure point guard (McConnell).

They Sixers may also find themselves picking their poison, so to speak, on defense against the Celtics.

If they focus heavily on stopping All-Stars Kemba Walker and Jayson Tatum, then Jaylen Brown and Gordon Haywood are bound to torch them.

“They have four players that can get 30 on a given night,” Brown said. “And they play well together. ... I feel like their ability to put points on the board, their ability to make threes, their ability to create their own shots, the four of them, is just lethal.”

Defensively, the Sixers don’t match up well against the Celtics. Richardson and reserve Matisse Thybulle are legitimate perimeter defenders. If healthy, Glenn Robinson III (left hip pointer) may be able to contribute off the bench. The problem is that Boston is loaded with long, athletic wing players and they’re going to attack the mismatches.

How the Sixers defend Walker, Tatum, Brown, and Haywood will have a huge impact on the series. That could be a scary situation for a Sixers team that surrendered 53 points to T.J. Warren and 51 to Damian Lillard in seeding games.

So we’re about to find out, starting Monday, if the Sixers were correct about being built for the playoffs.