The Knicks and the Celtics could not have seemed more separated when they met in Boston to open the season.

After the Celtics received their championship rings that October night, they overwhelmed the revamped Knicks with an impressive 29 made 3-pointers, equaling a record.

Despite more than half a season passing, the upgraded Knicks found themselves incapable of seeking revenge or catching up with the second-seeded Celtics in the Eastern Conference standings. Their disappointing and messy 131-104 loss to Boston on Saturday night at the Garden left the crowd disheartened.

Even though Jalen Brunson stood out with 36 points for the team, the Knicks’ overall record dropped to 34-18. Forward OG Anunoby was absent for his third consecutive game due to a sprained right foot.

Karl-Anthony Towns and Josh Hart, who both had landed on the injury report before the game with nagging knee issues, and fellow starter Mikal Bridges, had largely ineffective games as the Knicks were outrebounded 28-18 in the first half and a whopping 48-30 overall.

Towns managed a season-low nine points on 3-for-8 shooting in 28 minutes, while Hart finished minus-31 with three turnovers in 38 minutes.

Unstoppable All-Star Jayson Tatum buried seven 3-pointers and netted a game-high 40 points, while Payton Pritchard contributed 25 off the bench for the Celtics (37-16), who played without starters Kristaps Porzingis (illness) and Jrue Holiday (shoulder).

“They’re a tough matchup. They’re the defending champion,” Knicks coach Tom Thibodeau said. “They’re strong on both sides of the ball. They can spread you out. They can attack you off the dribble. They share the ball. You have to be very disciplined. You have to be able to make a second and third effort and be tied together, and sometimes they have the ability to make tough shots, and you’ve got to do it time and time again.

“Obviously, the Celtics have a rich history. The battles have been tough over the years. We know what it means to a lot of people.”

Opening Night meant a little extra for the Celtics and their hometown fans with a banner-raising ceremony at TD Garden followed by a 132-109 thrashing of the Knicks on Oct. 22, with the 29 Boston 3-pointers spoiling the Knicks debuts of Towns and Bridges.

Tatum scored the first five points of Saturday’s game on a driving dunk and Boston’s first of 19 3-pointers, while the Knicks clanked their first 10 shots to trail 12-2 before five minutes had elapsed.

Bridges (11 points 5-for-15) finally nailed a short jumper for the Knicks’ first field goal with 6:56 to go in the quarter, but another Tatum trey helped push the Celtics cushion to 17 late in the period.

The Knicks converted just six of 23 shots in the opening 12 minutes, and they trailed 30-19 entering the second quarter.

Towns, who had been downgraded to questionable earlier in the day due to a recurrent knee issue, drained his second 3-pointer to close the gap to single digits.

But Pritchard netted five straight points and two more Tatum triples made for an 18-point game nearly midway through the period.

Even with Brunson’s 18 first-half points — including 11-for-11 from the free-throw line — Tatum managed 16 for the Celtics, and the Knicks still were behind by 13 (61-48) at intermission.

Still, the Knicks initially responded after Thibodeau went with Miles McBride in place of Precious Achiuwa to open the second half.

Brunson pumped in eight points, Towns threw down a one-handed stuff and Bridges knocked down a right-side 3 during a 19-9 Knicks spurt to open the third to close within three.

But the Celtics managed 19 of the next 22 points, including three free throws after a McBride foul and two 3-pointers by Derrick White (17 points) to enter the final period with a 96-76 advantage.