Volkswacht Bodensee - Celtics overpower Mavericks 107-89 in game one of the NBA Finals

Porzingis, who missed 10 games after straining his right calf in the first round of the playoffs, made an immediate impact on his return as the Celtics built a 29-point lead in the first half then thwarted the Mavericks' third-quarter surge to gain the upper hand in the best-of-seven championship series in front of a raucous home crowd.

Porzingis came off the bench against his former team and scored 11 points with three rebounds and a pair of big blocks as Boston jumped to a 37-20 lead at the end of the first quarter.

After eight lead changes in little more than six minutes, the Celtics began to impose themselves, pulling away with the help of seven three-pointers in the first quarter alone and keeping up the relentless pace as the Mavs struggled to get their offense firing.

Boston finished with 16 three-pointers on a whopping 42 attempts. Jaylen Brown scored 22 points to lead six Celtics players who scored in double figures.

Porzingis finished with 20 and Jayson Tatum scored 16 points with 11 rebounds and five assists.

- Doncic scores 30 -

Dallas star Luka Doncic scored 30 points and grabbed 10 rebounds, but Kyrie Irving was limited to 12 points on six-of-19 shooting.

Despite his struggles, the Mavs managed to slice the deficit to eight points in the third quarter, only for the Celtics to pull away again.

"It's a game of runs," Tatum said. "This is the NBA Finals, they're not going to go away easy. We just had to respond and we did a good job of that."

Doncic, who has been playing through a right knee injury and a sore left ankle, struggled to find his shot. He picked up the pace in the second quarter, but Dallas couldn't find a way to slow the Celtics -- who pushed their lead to 29 points, 58-29, on Tatum's three-pointer with 4:11 left in the first half.

That capped a 14-4 scoring run that included a steal and driving dunk from Brown.

The Celtics' early surge had TD Garden rocking, the crowd featuring luminaries from around the sports world including Manchester City manager Pep Guardiola.

Actor Mark Wahlberg and brother Donnie were in attendance on a night when both teams paid tribute to late Celtics great Bill Walton, who died in May at the age of 71 after a battle with cancer.

Dallas made a push to start the third, when the Celtics went cold from three-point range and Dallas heated up.

Doncic drilled a trey to cut the deficit to 72-64 with 4:28 left in the period.

Boston had the answer, with a cutting dunk from Porzingis keying a 14-0 scoring run that included Brown's rejection at the rim of Derrick Jones Jr. and another Brown block on Irving.

Doncic scored 10 points in the third, but three-pointers from Tatum, Al Horford and Brown saw the Celtics take an 86-66 lead into the fourth.

Boston will try to double their advantage when they host game two on Sunday.

B.Baumann--VB