They’ll call it the Isaiah Thomas Tooth Game. Surely they will. It will occupy its own quirky place in Boston Celtics lore. And it gave the Celtics a crucial 1-0 advantage over the Washington Wizards in Game 1 of an Eastern Conference semifinal series that, if Sunday was any indication, could be just as thrilling and just as tight as expected.

Less than 12 hours after returning to Boston after attending his sister’s funeral and delivering an emotional eulogy, Thomas had a tooth jarred from his mouth, then led the Celtics back from an early 16-0 deficit to a 123-111 Game 1 win.

Thomas had 33 points on the afternoon — 31 in the first three quarters, and 30 after an Otto Porter elbow sent one of his front teeth flying to the Boston Garden floor. He hit two early threes to help Boston recover from Washington’s game-opening 16-point sucker punch, then took over in the third as the Celtics turned a 64-59 Wizards lead into a 95-80 lead of their own.

Thomas lost his tooth with the score at 20-5, and eventually went back to the locker room to have it “repositioned” in his mouth — which, if executed correctly, is an actual medical procedure, though it won’t replace real dental work in the future.

With the tooth back in place, Thomas returned to the game in the second quarter. It would eventually come back out of his mouth later in the afternoon, though.

“It just bothers me to talk,” Thomas said postgame. “My tongue goes right through my tooth. … Hopefully we can replace it as soon as possible.”

“Maybe that tooth was holding him back a little,” Brad Stevens quipped after the game.

Thomas fully got back into his groove in the third alongside a small-ball unit featuring Marcus Smart, Avery Bradley Jr., Jae Crowder and Al Horford. The spread look killed Washington in the second half. Crowder had 24 points on 6-of-8 from beyond the arc. Horford had 21 points, 10 assists and nine rebounds, and helped Boston pull through a late Washington push in the fourth. Bradley had 18 points and four steals.

But the story was Thomas — and the story really wasn’t his tooth, but rather his grief, and everything that has transpired over the last two weeks. He landed in Boston at 4 a.m. Sunday morning, and was reportedly at the arena by 10. “Basketball — when I’m on the court — it just keeps me going,” he told ESPN’s Doris Burke after the game. “I do everything for my sister now.”

“We know it’s not going to be peaches and cream all the time,” Thomas said when asked how he and the team have remained unaffected by adversity. “We’ve always played with our backs against the wall. Tonight, we definitely didn’t want to be down 16-0, but … it happens.”

Indeed, it happened. Washington opened the series with a barrage of offense that stunned the early-afternoon crowd in Boston. A 9-0 run forced Brad Stevens to take time. But a timeout couldn’t stop the Wizards, who went right at the East’s top seed and jumped out to a 16-0 lead:

Boston didn’t score until Thomas, with his mouth still intact, bought three free throws after Wall made contact with him coming around a screen. And the hosts didn’t have a field goal to their name until the 6:40 mark of the first quarter.

Then Thomas’ tooth went flying, and, subsequently, so did the threes. Thomas hit two quick-trigger long-range jumpers to get the home crowd going. That was before he had the tooth re-affixed to his mouth.

Boston gradually pulled itself back into the game despite the continued success of Washington’s offense. Marcin Gortat bullied the Celtics inside, just as Robin Lopez had early on in Round 1. Stevens briefly went to Amir Johnson alongside Horford, but quickly realized the way to combat Washington’s offensive rebounding and paint scoring was to not combat it, but rather exploit advantages in other aspects of the game. For the most part, Boston stayed small, and hurt Washington with ball-movement and 3-point shooting on the offensive end.

The course of the game was really altered when Scott Brooks went to his bench unit, and that bench unit was as bad as feared. Kelly Olynyk, off the Celtics bench, capitalized with 12 first-half points. Here’s a quick look at some Wizards first-half plus/minus numbers:

John Wall: +18
Bradley Beal: +11
Otto Porter: +16
Marcin Gortat: +13

Brandon Jennings: -13
Bojan Bogdanovic: -14
Jason Smith: -6 in just two minutes

The Celtics erased the deficit while a weakened Wizards lineup was on the court, and tied the game at 42 not even midway through the second quarter. Washington’s starters regained the lead late in the half, but Boston had stabilized itself after the early wobbles.

A crucial play late in the first half actually turned out to be a Markieff Morris jumper that gave Washington the lead. Morris landed on Horford’s foot, rolled his ankle, and didn’t return to the game in the second half.

Without Morris — who said he’ll be back for Game 2 — Washington’s already suspect depth was further exposed. In the third quarter, Thomas spurred the Celtics’ charge. His kick to Crowder for a three with 6:55 to play gave Boston its first lead of the game. Thomas scored 12 in the third and dished out two assists as the Celtics outscored the Wizards 36-16 in the period. They were up 15 going into the fourth — a pretty remarkable 31-point turnaround going back to the first quarter.

But then it was the Wizards’ turn to respond. They opened the fourth on 9-0 run, and the two players who you’d least expect to lead a comeback did just that. The bench duo of Jason Smith and Bojan Bogdanovic scored 15 of 19 points to bring Washington back to within three.

Boston recovered, though, and, behind Horford and 3-point shooting, reclaimed a 10-point lead. Crowder hit his sixth three. Rookie Jaylen Brown came in cold off the bench, hit one deep bomb and assisted on another.

Rather than going back to Thomas again and again in the fourth, the Celtics zipped the ball around the court and spread the wealth to regain control and hold on for a pivotal Game 1 victory. They’ll look to extend their advantage to 2-0 in Game 2 on Tuesday.