The Boston Celtics again stand alone among NBA champions.

Jayson Tatum had 31 points, 11 assists and eight rebounds as the Celtics topped the Dallas Mavericks 106-88 on Monday night to win the franchise’s 18th championship, breaking a tie with the Los Angeles Lakers for the most in league history.

Boston earned its latest title on the 16th anniversary of hoisting its last Larry O’Brien Trophy in 2008. It marks the 13th championship won this century by one of the city’s Big 4 professional sports franchises.

Jaylen Brown added 21 points. Jrue Holiday finished with 15 points and 11 rebounds. Center Kristaps Porzingis also provided an emotional lift, returning from a two-game absence because of a dislocated tendon in his left ankle to chip in five points in 17 minutes.

It helped the Celtics cap a postseason that saw them go 16-3 and finish with an 80-21 overall record. That .792 winning percentage ranks second in team history behind only the Celtics’ 1985-86 championship team that finished 82-18 (.820).