Mazzulla continued to have faith in his reserves as the Kings gradually reduced an 18-point fourth-quarter deficit to a one-point lead in the dying seconds.

These reserves displayed composure in the dying seconds, as Boston prevailed by a razor-thin margin on Friday at TD Garden. With 7.1 seconds remaining, Xavier Tillman nailed a clutch floater that gave the Celtics a one-point advantage. Boston then made its final stop to secure a 101-100 victory.

The Celtics (61-16) were led by Payton Pritchard’s 21-point effort, Kristaps Porzingis’ 20 points and 11 boards, and Jayson Tatum’s 17-point effort. Domantas Sabonis contributed 16, while De’Aaron Fox scored 40 for the Kings (44-33).

In the opening minutes, both teams labored offensively, with the Celtics trailing by three points at the 5:41 mark. Pritchard and Tillman contributed to Boston’s reestablishment by executing a combination of astute passing and judicious rushing plays.

Despite the slow start, the Celtics concluded the quarter on a lengthy 24-7 run, establishing a 27-15 lead through one period. Tatum contributed six points, while Porzingis scored seven. Svi Mykhailiuk made a three-pointer as well. Luke Kornet, the crowd favorite, delivered the highlight by leaping in for a trampoline putback touchdown.

Mazzulla utilized the nine-deep fielding that has benefited him throughout the season, and he maintained that reliance in the first quarter. Boston completed 9 of 10 from 1 for 10, whereas Sacramento remained frigid and completed 23.8 percent of its attempts.

Kornet maintained a positive ambiance in the second period by deftly converting an alley-oop pass from Al Horford. Jrue Holiday executed a deft step-back three, Pritchard capitalized on an opportune roll, and Tillman intercepted a hustle rebound before passing the ball to Porzingis for a rhythmic three.

With 4:45 remaining, that tied the game 49-33 for the Celtics. However, Fox ignited a Kings frenzy that reduced Boston’s lead to 54-50 at halftime. The Kings’ 32.1 percent from three-point range was not much better than the Celtics’ 29.2 percent.

Both teams experienced a sporadic first half, which resulted in a comparatively unpolluted beginning to the second.

With 9:02 remaining, Boston extended its lead to 66-52 on the strength of a 12-2 run, which was capped by a lovely sequence in which all five Celtics made contact with the ball. By declining a mediocre attempt, Tatum located Porzingis. Holiday and Porzingis each completed the extra pass, while Hauser allowed the defender to pass him while driving to the basket and locating a wide-open Horford for two.

Following a foul on a breakaway layup late in the quarter, Porzingis expressed his admiration for the Celtics supporters by pounding his torso and handing out a round of applause.

The Kings consistently limit the damage, reducing the deficit to 75-70 by the end of the quarter. With two seconds remaining, Pritchard sank a three-pointer, Porzingis blocked a shot, Hauser assisted Porzingis on an alley-oop, and Tatum drained a contested three-pointer.

With three games remaining, the Celtics increased their lead to 84-72, limiting Sacramento to 36.5 percent overall shooting. The Kings grew weary of Boston’s continuous ability to make the extra pass and its fluid ball movement as the evening progressed.

With 9:24 remaining, rookie Jordan Walsh checked in and contributed a desperation rebound. Despite Pritchard’s persistent cooking against the starters of Sacramento, the Kings were by no means defeated. 2:25 into the game, Fox reduced the deficit to 98-92 with a crucial three-pointer.

At the 27-second mark, Sacramento led 100-99 on a three-pointer by Fox, and Tillman then delivered the heroics. Ultimately, despite the lack of aesthetic appeal, it sufficed.