The Celtics are in the Eastern finals because they were better than the 76ers at the things that matter most

Jayson Tatum might wind up third in Rookie of the Year voting when it’s all said and done. But the week after both Donovan Mitchell and Ben Simmons headed home for the summer, he’ll still be playing, and he’s an awfully big part of the reason why.

The 2017 NBA draft’s No. 3 overall pick scored 10 of his team-high 25 points in the fourth quarter of Wednesday’s Game 5, including a critical layup with 22 seconds left, to help the Boston Celtics fend off a Philadelphia 76ers team fighting for its playoff lives. Thanks to Tatum’s scoring and timely two-way heroics from veteran linchpins Al Horford and Marcus Smart, the Celtics withstood Philly’s furious second-half comeback, regained control of the game in the final minute, and held on for a 114-112 victory in front of a raucous crowd at TD Garden.

The win completed a 4-1 Boston triumph in the conference semifinals, eliminating the upstart Sixers and moving the Celtics on to an Eastern Conference Finals rematch — of sorts, given the dramatic overhauls of both rosters since last May — with LeBron James and the Cleveland Cavaliers, who just swept their way through the No. 1-seeded Toronto Raptors. Game 1 tips off Sunday at 3:30 p.m. ET in Boston.

The Celtics have elite talent, too

After a 14-point first half in which no Sixer guard or wing could credibly check him, the 20-year-old Tatum fought through a thumb injury that quieted him in the third quarter to roar in the fourth, repeatedly fighting his way to the foul line for sorely needed points as the game slowed down and the defensive intensity picked up. Tatum’s the-future-is-now wing parter, second-year guard Jaylen Brown, was also brilliant in his first start since suffering a hamstring injury in Game 7 of Boston’s first-round series against the Milwaukee Bucks, scoring 24 points on 10-for-13 shooting with four rebounds, two assists and two blocks in 31 minutes of work.

Horford continued to be everything Boston needs him to be in a postseason push without expected All-Star running buddies Kyrie Irving and Gordon Hayward, scoring 15 points with eight rebounds, five steals and three assists in 39 minutes, and making multiple clutch plays on both ends of the floor midway through the quarter. And with the game in the balance in the final minute, it was Smart — the heart and soul of Boston’s defense, the agent of chaos on whom head coach Brad Stevens calls to restore order — who put his fingerprints on the finish.

After Tatum missed an open layup with one minute to go, Smart soared in for the offensive rebound and putback to tie the game at 109-all. On the Sixers’ next trip, the 6-foot-4 Smart bodied up 6-foot-10 Philly forward Dario Saric in the post, absorbing the back-down contact from the bigger man and forcing a turnover that got Boston out in transition, culminating in Smart rifling a pass to Tatum, cutting along the baseline under the basket, for a layup that would give the Celtics a two-point lead with 22 ticks left:

The Sixers had a chance to tie on the next possession, and they worked the ball into their horse, All-Star center Joel Embiid, who had shaken off a quiet start to do some real damage on the block in the second half. He got the ball on the left wing, facing up on series-long nemesis Aron Baynes, and went to work, banging his way into position near the basket …

… but he missed two point-blank looks at the basket through contact, and on his third attempt, had the ball stripped by recent trash-talk target Terry Rozier. The ball went out off Embiid’s leg, giving the Celtics possession with 10.8 seconds to go.

A Marcus Smart game gets a Marcus Smart ending

After a pair of clutch free throws by Rozier capped an 8-0 Boston run and pushed the Celtics’ lead to four, J.J. Redick drilled a wild 3-point bomb on the move from two steps behind the line at the top of the arc, getting Philly back within one with four seconds remaining. On the ensuing inbounds, Horford gave the ball back to Smart, allowing the Sixers to foul a shooter who’d just missed a pair of freebies with 2:13 to go in the frame. He missed the first here, too, setting up a scenario in which Philly — without a timeout, needing to go the length of the floor for an equalizer — had to anticipate him missing on purpose to try to run out the remaining 2.4 seconds.

Smart tried to miss; it just didn’t go his way. So, naturally, he went and made up for it:

After inadvertently banking in his intended miss, Smart tracked back on the other end of the floor, read the eyes of Sixers point guard Ben Simmons, outjumped Robert Covington for the ball and intercepted Simmons’ Hail Mary pass. It sure looked like he traveled after coming down with it, but the officials’ whistles stayed silent, Smart chucked the ball into the air, and the buzzer sounded.

Game over, series over, and the Celtics were moving on, thanks in part to a predictably unpredictable and perfectly frenzied performance by Smart. He finished with 14 points, six rebounds, six assists and three steals in 33 minutes off Boston’s bench; he was a game-high plus-14, and even through miscues like his adventures at the free-throw line (he went 8-for-13 at the stripe on Wednesday), it felt like it.

Trust the growing process

After struggling in the early part of the series, Philly’s young stars stepped forward to try to extend the series on Wednesday.

Saric was the steadiest hand on the floor, scoring 27 points on 8-for-14 shooting with 10 rebounds, four assists, a steal and a block in a team-high 40 minutes. He scored nine in the fourth quarter, including a huge 3 off a kickout from the post by Embiid to put the Sixers on top with 3:30 to go and a nifty reverse layup after sealing Smart in the post to give Philly a four-point lead with 1:37 left.

With Boston selling out to limit Philly in transition and from the 3-point arc, they needed Embiid to go to work down low, and he did just that in the second half. The mammoth center scored 15 of his 27 points after intermission, to go with 12 rebounds, four assists and four blocks in 39 minutes, fighting through fatigue to change the game in the fourth quarter with his defensive work. He was scoreless in the final four minutes, though, and those missed layups figure to haunt the 24-year-old marvel all summer long.

Ditto for Redick, who’d been blanketed by Smart for most of the night but managed to find some daylight late, and who had a crystal clear look at a left-wing 3 that could’ve given Philly a five-point lead with 1:11 to go …

… but the Sixers’ veteran sharpshooter couldn’t connect, leaving the door open for Smart’s put-back to tie the game on the next possession.

Simmons started Game 5 aggressively, looking to touch the paint early and often, and looked for his shot — even if some of those shots were wild flails really only in the vicinity of the rim — to try to put pressure on the Celtics’ defense. He brought it late, too, scoring six points of his 18 points and dishing four of his six assists to help bring Philly back from a mid-fourth deficit, before ending his season on the sour note of a long-ball turnover tossed into the hands of Smart.

Ultimately, though, Philly simply did too many things wrong too often to win a playoff series against an opponent this tough. There were the avalanche of missed 3s off the fingertips of the 76er shooters who’d buried big shots throughout the regular season and in Round 1 against Miami. There was Simmons’ hesitation in transition, bricked finishes around the rim and his inability to make Boston pay for sagging off him with a midrange shot. There were Embiid’s ill-considered jumpers and poorly thrown passes, his failures to box out and struggles to defend in space.

There was Robert Covington’s largely nightmarish series, and the miscommunications that literally had players bumping into one another multiple times during half-court sets and bringing their defenders to the ball to clutter up post-ups. There was coach Brett Brown holding onto his timeouts in Game 1 as Boston ripped off runs, waiting until Game 4 to go all-in on playing T.J. McConnell (nine points, six assists, five rebounds, two steals, one turnover in 37 minutes in Game 5 while helping hound Rozier into 4-for-15 shooting; McConnell was a team-high +41 in 114 minutes in this series) and burning his timeouts to try to stall runs in Game 5, leaving Philly unable to advance the ball on the final play that ended with Simmons’ failed prayer.

It was sloppy, tight, full of bumps and bruises for a team with immense talent and flaws to match — one learning its lessons in real time against an opponent that repeatedly played poised, low-turnover, high-execution, incredibly sharp basketball. This Celtics team is plenty green in its own right, leaning as much as it does on young guns like Tatum, Brown and Rozier, but also one that’s led by some dudes who know precisely what to do, when to do it, and how to get it done.

The craziest thing? One of them’s a 20-year-old from St. Louis who, this time six years ago, was asking LeBron if he followed back.

Starting Sunday, Tatum and the rest of these Celtics are going to get a hell of a lot more than a follow from LeBron. After watching what he just did to Toronto, you’d be within your rights to feel a little ill at ease about betting on the higher seed again.

But after watching what Tatum and company just did to Philly — and watching all they’ve accomplished since seeming left for dead after losing Hayward on opening night, and again after losing Irving a month before the start of the playoffs — you’d be within your rights to give it a second thought, too. These Celtics don’t think they’re playing with house money, and they’re not thinking about how they’re not supposed to be here; all they’re thinking about is what’s next, and what they have to do to keep playing.

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Dan Devine is a writer and editor for Yahoo Sports. Have a tip? Email him at devine@oath.com or follow him on Twitter!

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