The Boston Celtics have romped to a 18-point victory over the Dallas Mavericks to seize the initiative in the NBA Finals despite a quiet game from franchise cornerstone Jayson Tatum. 

Jaylen Brown scored 22 points while Kristaps Porzingis added 20 in his first game in more than a month as Celtics powered to a 107-89 victory in Game 1 on Thursday night.

Derrick White finished with 15 points for Boston, who led by 29 points in the first half and connected on 16 three-pointers in a powerful start to their quest for an 18th NBA title.

Tatum only managed 16 points on 6/16 shooting and came up with six turnovers but added 11 rebounds.

Porzingis, who had been sidelined since April 29 with a strained right calf, came off the bench and provided an immediate spark, adding six rebounds and three blocks in 21 minutes. 

Dallas cut the deficit to eight points in the third quarter, but Boston quickly pulled away again.

Luka Doncic led Dallas with 30 points. P.J. Washington added 14 points and eight rebounds, but Dallas couldn’t find offensive consistency beyond that, totalling just nine assists on their 35 field goals for the game.

Aussie Josh Green enjoyed 20 minutes of game time for the Mavericks for three rebounds and three points, while compatriot Dante Exum played five minutes for two rebounds and one assist.

Former Celtic Kyrie Irving struggled throughout, finishing with 12 points. He received a loud and extended chorus of boos Thursday when he was introduced before the game. It continued throughout the game whenever he touched the ball.

The treatment came after Irving sparred with Boston fans and was fined for using an obscene gesture during a 2022 playoff visit to TD Garden.

The Celtics, seeking their first championship since 2008, showed little rust from their 10-day layoff after sweeping the Indiana Pacers in the Eastern Conference finals.

They flowed with energy throughout, sharing the ball in the halfcourt and getting the ball to shooters for open 3s. They also attacked the interior of the Dallas defence and got to the rim for several dunks.

Meanwhile, apart from Doncic, who shot 12 of 26 from the field, Dallas struggled early to get into its sets and couldn’t find a consistent groove offensively.

The Mavericks led by one midway through the first quarter. The Celtics responded by outscoring them 44-16 to make it 58-29 in the second.

Dallas used a 35-14 run, including 15 points by Doncic, to cut Boston’s lead to 72-64. But Boston ended the third quarter with a 14-2 spurt to get it back up 86-66 entering the fourth.

Porzingis ended his 10-game hiatus when he came off the bench with 7:17 left in the first quarter in place of starter Al Horford. With the exception of a white compression sleeve on his right leg, it was hard to tell Porzingis was coming off an injury.

He knocked down a pair of free throws after being fouled by Doncic. A possession later, the Latvian connected in his first field goal when he dropped on a short jumper over Doncic.

Minutes later he got loose in the paint for a two-handed dunk over Derrick Lively. On Dallas’ next possession, Porzingis was there to swat away Jaden Hardy’s layup attempt. The Celtics pushed the ball up the court and got the ball back to their big man, who calmly buried a 16-footer.

It was part of a 17-5 surge by Boston over the final 5:24 of the quarter that saw Porzingis go 4 for 5 from the field, score 11 points, block two shots and grab three rebounds.

Porzingis finished the half with 18 points on 7-of-9 shooting.