Minus Jaylen Brown, Celtics beat the Nets behind Jayson Tatum, Marcus Smart

© Mary Altaffer With the Celtics playing without Jaylen Brown, the Nets turned up the defensive pressure on Jayson Tatum.

NEW YORK — With Jaylen Brown and Al Horford sidelined, and Jayson Tatum scuffling through a frustrating offensive game, the Celtics could have been in a difficult spot Thursday against the Nets, even without Kevin Durant.

But this Boston team prides itself on its depth. The Celtics have insisted all year that dynamic sixth man Malcolm Brogdon would start for most other teams. They have insisted that Payton Pritchard, who has fallen out of the rotation when this group is full, would have an essential role on most other teams.

And in this game, those two combined to make seven baskets in a row during a key stretch that started late in the third quarter and bled into the fourth, helping the Celtics seize a 109-98 win, their fifth in a row.

Tatum finished with 20 points but made just 7 of 22 shots. Boston won this game with its balance, as eight players scored eight points or more. Marcus Smart had 16 points, 10 assists and 6 rebounds in his first game after missing two with a knee contusion.

The Celtics were missing Brown after he suffered an adductor strain in Wednesday’s win over the New Orleans Pelicans.

With Smart and Tatum on the bench at the start of the fourth against the Nets, Pritchard and Brogdon converted two field goals apiece over a two-minute stretch, sparking the 8-2 run that gave Boston a 92-84 lead.

Boston stretched its lead to double digits before Brooklyn pulled within 96-89 on a T.J. Warren 3-pointer with 5:43 left. But the Nets were held to just nine points from there, and Boston coasted to the finish.

Kyrie Irving had 24 points to lead the Nets, who were playing their first game since Durant sprained his right knee.

With the victory, the league-leading Celtics improved to 31-12. They have won five straight games and eight of 10. The Nets lost for only the second time in 16 games.

Observations from the game:

⋅ Smart’s impact at both ends was evident in the first half, even though he made just 2 of 8 shots. Early in the first quarter he lost the ball on a drive, managed to gather it, then whipped a perfect no-look, over-the-shoulder pass to Robert Williams for a basket. Smart had 6 points, 8 assists, and 5 rebounds in the first half, and just about everything ran through him.

⋅ Al Horford sat out to rest his back, and coach Joe Mazzulla took the opportunity to increase Williams’s workload. Williams had not played more than 23 minutes since September knee surgery but logged 14 in the first half alone. He hasn’t had many dominant stretches yet, but he’s staying healthy and he looks mobile. It’s a great development.

⋅ Luke Kornet once again stepped in admirably, too. After a strong game while Williams sat Wednesday, he was Boston’s best player for stretches of the first half Thursday. During one segment he scored inside, hit a 3-pointer from the right corner, and put back a Tatum miss. Kornet was 4 for 4 from the field before the break.

⋅ Tatum has looked a bit tired the last two games. Through the first three quarters he air-balled three 3-pointers, and even had an uncontested rebound bounce off his hands and out of bounds. But he’s still capable of turning slow nights around in an instant. On Wednesday, he scored 14 of his 31 points in the first nine minutes of the fourth. On Thursday, he scored seven points over the first 22 minutes, 46 seconds of game action before matching that total in the final 1:14 before halftime.

⋅ The Nets stretched their lead to 43-34 on a Seth Curry basket three minutes into the second quarter, and Mazzulla instantly turned to Smart and Tatum and told them to go check in. But about 90 seconds passed without a stoppage in play, and Smart and Tatum watched as the bench-heavy unit fought back with a 8-0 burst. An important sequence.

⋅ In the third quarter, the Nets and Celtics took turns hitting each other with mini runs, but neither was able to extend one into something more permanent. Brogdon has plugged leaks often this season, and his two 3-pointers late in the third really lifted the Celtics from a sleepy stretch. Boston took an 84-82 lead into the fourth.

⋅ Ben Simmons had 13 assists through the first three and a half quarters and played good defense on Tatum. But his lack of confidence as a scorer was particularly glaring with Durant out. He probed in the paint several times, and either passed up simple shots or looked awkward missing them. And these were four-footers, not 3-pointers.