Boston guard Marcus Smart drives to the basket past Brooklyn guard James Harden during a March 11, game in New York. The teams meet in the first round of the playoffs starting Saturday at 8 p.m. Adam Hunger/Associated Press

The Celtics are officially in the playoffs – that significance isn’t lost on Jayson Tatum, who poured in 50 points to beat the Washington Wizards, 118-100, in the play-in game on Tuesday night.

Tatum, the No. 3 pick in the 2017 NBA Draft, and every single year since the Celtics reached at least the second round of the playoffs.

“It’s my fourth year in a row,” Tatum said of being in the playoffs. “I don’t take that for granted. Myself and everybody else, we’re excited. It’s the playoffs, so we just have to get ready for the next game.”

Boston is far from guaranteed a spot in the second round this season with the No. 2-seeded Brooklyn Nets up next – one of the championship contenders and arguably the most talented team in the league with the trio of James Harden, Kevin Durant and former Celtic Kyrie Irving.

Game 1 is Saturday at 8 p.m. in New York.

But the Nets have some other intriguing pieces in the rotation, all led by first-year Nets Coach Steve Nash. How those pieces fit together during the high-stakes playoffs will interesting. The Nets have battled injury issues to their star trio all season, but are trending toward full health ahead of the playoffs. The Celtics are on the other side of the health spectrum, with Jaylen Brown is lost for the season, which severely limits their ceiling.

Boston Coach Brad Stevens was complimentary of the Nets, calling them “the most talented team that’s been assembled since I’ve been in the NBA.” Stevens admitted he has a difficult time seeing Brooklyn lose at any time in the playoffs, but that’s his task to lead the Celtics ahead of their daunting first-round matchup. The Nets swept the Celtics during the season series, a perfect 3-0.

“It’s really hard to make the NBA playoffs,” Stevens said. “I just told our guys in there everyone’s path is different, and every year presents unique challenges, some years more than others. We’ve been through a lot, so we’re hardened in a lot of ways.”

Here are four things to know about the Celtics-Nets first-round series:

That offense is lethal.

Despite all the injuries, chemistry and maintenance concerns, the Nets were still the most efficient offense in the league. Brooklyn posted a 117.3 offensive rating this season, No. 1 in the NBA, even though they were battered and bruised all season, especially to their star trio.

Much of that makes sense, though. Having just one of Irving, Harden or Durant completely changes the dynamics of an offense. Pairing any two of them together makes the Nets one of the most offensively-potent teams in the league. The still-unknown potential of the trio playing extended minutes together is what makes them so deadly.

Harden knows how to single-handedly carry an offense dating back to his Houston days, when he was a one-man wrecking crew and scored at historical rates. Durant and Irving have played in roles where they’re not the primary option, but they can take the scoring duties in a flash. The Celtics’ defense has struggled for spurts this season; how they attempt to stop the Nets will determine if they can hang around in the series.

The Nets aren’t all perfect

While praise can be thrown upon the Nets’ superstars, they have other issues on the roster. While their offense was sparkling, the defense lagged behind for much of the season, finishing at a 113.1 defensive rating, 22nd in the NBA. Championship contenders usually pair top offenses and defenses, but the Nets might be able to outscore their opposition anyway.

Irving, Harden and Durant only played in eight games this season together as it seems at least one of their trio was injured at varying points of the season. Harden was out for weeks because of a hamstring injury, Durant only played in 35 games this season and Irving suffered a facial contusion late in the season (though he appears to be OK). The lack of playing time together is just another question mark for the Nets.

The rest of the roster

While the Nets’ depth looked to be gutted after trading for Harden at the beginning of the season, they still have plenty of intriguing players to fill out their roster. They signed Blake Griffin from the buyout market, and while he isn’t his All-NBA self anymore, he’s a serviceable veteran who can take some of the playmaking duties.

Other players like Bruce Brown Jr., Nicolas Claxton, Jeff Green and Landry Shamet should get some minutes as role players. The Nets got some good news when Nash said Tuesday that Joe Harris should be available for Game 1 after he missed the final three games of the regular season with a gluteal strain. Harris is one of the best shooters in the league and shot a scorching 47.5% on 3-pointers this season.

A reunion

Irving hasn’t played in front of a TD Garden crowd since he left following the 2019 NBA playoffs. That won’t be the case as he will play in front of a reduced-capacity crowd at the minimum. If the Celtics can force a Game 6 and it’s after May 29, Irving might even play in front of a 100% capacity crowd at the TD Garden.