Jayson Tatum and the Boston Celtics will face the Philadelphia 76ers in the first round of the NBA playoffs. Mike Ehrmann/Pool photo via the Associated Press

The No. 3 seed Boston Celtics take on No. 6 Philadelphia 76ers in the first round of the Eastern Conference playoffs.

Here are nine questions as the series approaches.

1. How will the Sixers adjust to life without Ben Simmons?

The most obvious question is also the biggest one. The Sixers will be without one of their two stars for the extent of the series – Simmons suffered a subluxation in his knee and had an operation to remove a loose body. Philadelphia ruled him out for the season.

The Sixers may feel the lack of Simmons most defensively – versatile with his speed, strength and size, he was one of the few players on Philly’s roster capable of guarding Jayson Tatum.

Brad Stevens was asked about Simmons’ absence following Boston’s game against Washington on Thursday.

“They’re a heck of a team,” Stevens said. “In the games Simmons hasn’t played, they’re the No. 1 offense in the league.”

That stat, while probably true, might be a little misleading – filtering out all of Simmons’ possessions on cleaningtheglass.com, the Sixers have an 80th percentile offense, averaging 114 points per 100 possessions. That’s very good, but not No. 1 Offense Juggernaut good.

The defensive issues for Philly, meanwhile, will be real – the Sixers gave up 111.1 points per 100 possessions with Simmons out, which is just a 52nd percentile total.

2. So without Simmons, who guards Jayson Tatum?

The easy answer here is Matisse Thybulle, but Tatum has had some success against players who are smaller and quicker. Thybulle – who started 14 games as a rookie for Philly – bothered Kemba Walker in the pick-and-roll, so perhaps the Sixers try to limit that matchup again.

One thing to watch with Tatum: He struggled twice against the Houston Rockets, who threw bigger, burly forwards at him (P.J. Tucker, Danuel House, Robert Covington and even James Harden). Tatum has gotten better at selling contact and getting to the free-throw line, and his shot creation has spiked to near-shocking levels. Still, expect to see plenty of physical defense against the Celtics’ young star.

3. What is Boston’s strategy against Joel Embiid?

All year, media and fans wondered what the Celtics would do if they met Joel Embiid in a playoff series. Aron Baynes and Al Horford are gone (more on Horford in a minute), and Boston’s remaining bigs are either smaller (Daniel Theis), slower (Enes Kanter) or young and inexperienced (Robert Williams).

With Simmons out, the answer might simply be to defend Embiid 1-on-1 and cut your losses. Embiid is supremely talented on both ends, but winning a game with post-up offense in 2020 is difficult, and if Celtics’ defenders give great effort 1-on-1, he might wear down.

Alternatively, the Celtics could try to make Embiid into a playmaker by sending complicated doubles and hoping Philly won’t punish them behind the arc. That could work, but Embiid has an assist percentage of 18.5 – 94th percentile league-wide.

There really isn’t a perfect answer for a 7-foot-2 behemoth who can both power through and drop step around you. Fortunately for the Celtics, they have a few mismatches of their own.

4. Can the Celtics’ wings overwhelm Philadelphia?

One of Philadelphia’s biggest issues: How will a combination of Thybulle, Josh Richardson, Alec Burks and Furkan Korkmaz deal with the four-headed monster of Walker, Brown, Tatum and Hayward? Richardson and Thybulle are admirable defenders. Korkmaz can shoot. Burks has had some nice moments. But the Celtics have three All-Star-level wings and an All-Star point guard. That’s a lot of firepower, especially facing a team missing its best wing defender.

5. What will Al Horford’s role be?

Sixers fans are … less fond of Horford than Celtics fans were during his tenure with the team. Most, in a moment of truth, would probably admit that it isn’t Horford’s fault he was offered a four-year, $109 million deal. He didn’t assemble this roster full of mismatched talent.

But Horford struggled this season. He hit just 34.6 percent of his triples, a far lower total than Philadelphia needed to space the floor. The Sixers are 1.7 points points/100 possessions worse offensively in his minutes, and while he has helped boost the defense by 2.7 points/100 possessions, the Sixers planned to be a juggernaut on that end, not simply “solid.”

Lineups with Horford and Embiid together have been excellent defensively – giving up just 103.6 points/100 possessions, which is in the 95th percentile. A very limited sample size of those two without Ben Simmons on the floor suggests the defense could suffer and the offense could pick itself up, but that sample size is just 359 possessions. For context, Carsen Edwards was on the floor for 528 possessions this season.

The Celtics respect Horford, but he isn’t a great matchup against any of Boston’s best players – do you have him guard Brown in the Celtics’ starting lineup? Tatum? Either would likely be fine for Boston.

6. How much does Kemba Walker benefit from playing a smaller Philly team?

Ben Simmons at point guard didn’t work particularly well this season, but it did make Philly an awkward matchup for opponents. Where do you put your star point guard defensively when everyone is taller than 6-6? That was one of the promising features of this year’s Sixers team.

Now, however, Philly’s starting lineup is more traditional, which makes Walker’s life simpler. The Sixers may still throw Thybulle at him, but he will be able to guard Shake Milton and Raul Neto instead of Josh Richardson.

7. Who you got: Enes Kanter or Robert Williams?

On the one hand, this is perhaps the series most tailor-made for Kanter: His defense in the season opener against Embiid – 10 months ago at this point – was solid, and he’s the Celtics’ only player both tall and strong enough to make the Sixers’ superstar work.

But if the Celtics decide to defend Embiid 1-on-1 and overwhelm the rest of the squad, maybe Robert Williams makes more sense. After all, Kanter opens up pick-and-roll opportunities for Philadelphia’s guards, and the entire point of that strategy would be to limit the 76ers to one (admittedly enormous) advantage while the Celtics take the rest.

The guess here is that Kanter gets the first crack. Kanter is a veteran. Williams just started to look like a real rotation player four games ago. But a playoff series is all about adjustments, and the Celtics might have to try a few things against a center of Embiid’s caliber. Williams may get thrown into the fire.

8. Does the back-to-back thing matter?

For context: The Celtics have played the Sixers four times. Philly’s defense held the Celtics to 93 points in Boston’s season opening loss. In December, the Sixers won 115-109 after the Celtics played in Indiana the night before. A month later, the Celtics played the Sixers in Philadelphia one day after falling to the San Antonio Spurs at home and lost 109-98. Boston finally salvaged a win on Feb. 1 to stave off the season sweep.

How much of a factor were the back-to-backs? They didn’t help, certainly – especially since both involved travel. But the fact that the Sixers’ best, highest-usage player is a brutally difficult matchup for the Celtics’ roster specifically didn’t help either.

9. Is the bubble ready to expand?

Through practices, scrimmages and seeding games, the Disney World bubble held firm against coronavirus. For that, everyone involved – players, coaches, staffers, Adam Silver, etc. – deserves a ton of credit.

Now player families, friends and girlfriends can start filtering in (on a very limited basis). The bubble dynamic will shift a little bit. Here’s hoping the plan for the next stage is as rock-solid as it was for the first one, because the basketball has been electric.