BOSTON — One of the first people to congratulate Boston Celtics star Jayson Tatum on winning the NBA championship was his 6-year-old son.

“He told me that I was the best in the world,” Tatum said. “I said, ‘You’re damn right I am.'”

Tatum certainly looked like it on Monday night, recording 31 points and 11 assists as Boston locked up its league-record 18th title with a 106-88 blowout of the Dallas Mavericks in Game 5 of the NBA Finals.

Tatum also had eight rebounds while Jaylen Brown added 21 points, eight boards and six assists for Boston, which celebrated the 16th anniversary of its 17th title by completing a 16-3 playoff run.

The Celtics knocked off the Los Angeles Lakers in the 2008 Finals, and those two franchises shared the NBA record with 17 championships apiece entering Monday.

Brown was selected the Finals MVP, an award named after Celtics legend Bill Russell, after averaging 20.8 points, 5.4 rebounds and five assists. Brown admired Russell, making the honor all the more special.

“I can’t even put it into words,” Brown said. “Just Bill Russell and what he’s meant for me through my Boston journey, and his spirit. You know, everything that he stood for, just for this to be the Bill Russell MVP Award. … I don’t even know what to say. It’s unreal.”

Jrue Holiday had 15 points and 11 rebounds and Derrick White chipped in 14 points as Boston bounced back from a 122-84 loss to wrap up the best-of-seven series.

“We did it together,” Holiday said. “I hope that when people watch us play, they see the joy that we play with, that we love playing together, and we got it done together. I feel like that’s the most important thing.”

Luka Doncic paced the Mavericks with 28 points and 12 boards, but he committed seven turnovers. Kyrie Irving finished with 15 points and nine assists for Dallas, and Josh Green netted 14 points.

Doncic is confident that the Mavericks’ best days are ahead of them.

“I feel great. We did some great moves,” Doncic said, referring to the team’s roster changes. “I would say we’ve been together for five months. I’m proud of every guy that stepped on the floor, all the coaches, all the people behind. Obviously, we didn’t win (the) Finals, but we did have a hell of a season and I’m proud of every one of them.”

After Dallas called a timeout with 3:11 left in the second quarter, trailing by 11 points, Boston completely broke the game open.

The Celtics scored 17 of the next 24 points, six of which came from Brown. Payton Pritchard capped the outburst in jaw-dropping fashion, canning a 49-foot heave from half court at the buzzer to send Boston into the break with a 67-46 cushion.

“Payton is one of the best competitors and one of my favorite people in the world,” Celtics coach Joe Mazzulla said. “Just the way he competes, the professionalism and just for his ability to take pride in stuff like that. He’s really grown as a player this year to becoming a well-rounded player on both ends of the floor, and he won us games.”

Holiday’s layup pushed the Celtics’ lead to 78-52 with 9:10 to go in the third quarter. Green then converted a putback and knocked down a 3-pointer as part of a 10-2 run that got the Mavericks within 80-62.

Dallas later got the deficit down to 17, but Boston took an 86-67 lead into the fourth.

The Celtics were on top by at least 18 the rest of the way.

“It snowballed quickly. The turnovers led to easy baskets or wide-open threes (for the Celtics),” Mavericks coach Jason Kidd said. “So they took advantage of that, and we couldn’t keep scoring or keep pace with them. We got good looks that just didn’t go down for us.”

A three-point play from Tatum put the Celtics up 46-31 with 7:08 remaining in the first half, but Dallas then took over down low. The Mavericks scored all of their points in the paint during an 8-2 spurt to get within nine before Al Horford stemmed the tide with a hard-nosed layup.

Horford’s bucket came just before the Mavericks’ timeout that preceded Boston’s game-changing run.

Boston came to life in the final 1:39 of the first quarter, ripping off nine unanswered points to take a 28-18 lead into the second.

The Celtics wound up shooting 42.7 percent from the floor. Dallas shot 44.9 percent overall but was outscored by 10 points at the foul line, was outrebounded 51-35, and committed 13 turnovers to Boston’s nine.

–Nick Galle, Field Level Media