DONE DEAL: Celtics FINALLY WON THE MATCH OF SIGNING KEY MAN FOR A WHOOPING SUM OF $67M FOR A CONTRACT OF…

PORTLAND — The Boston Celtics aren’t taking 50 wins this season for granted.

Jaylen Brown scored 27 points, Jayson Tatum added 26 and the Celtics beat the Portland Trail Blazers 121-99 on Monday night despite the absence of two key starters.

Jrue Holiday and Kristaps Porzingis were sidelined with injuries for the Eastern Conference-leading Celtics, who reached the 50-win milestone for the third straight season.

“At this point of the season, to have 50 wins, it means we’re doing something right,” Tatum said. “The scary part is, we can get better.”

The Celtics, the first team this season to reach 50 wins, have already clinched a playoff spot with 18 games remaining.

All the guys laugh because, around this time of year, I say the same thing — how much of an honor it is to be on this team,” Brown said.

Deandre Ayton had 22 points and 15 rebounds for the Blazers, who are second-to-last in the West. It was Ayton’s fifth straight double-double, tying the second-longest streak in his career.

Boston, which has won an NBA-leading 21 games on the road this season, pushed its lead to 20 points in the fourth quarter and had just three turnovers in the game. It was the second-fewest turnovers in a game this season: The Celtics had two in a January game against Denver.