CLEVELAND — The Knicks didn’t play many games at full strength over the final month of the regular season due to injuries, but their returning top players fronted them to an all-important victory in their playoff opener

Julius Randle scored 16 of his 19 points in the first half in his first appearance in more than two weeks, and Jalen Brunson bounced back from early foul trouble to net 21 of his 27 after halftime for a taut 101-97 victory over the Cavaliers in Game 1 of their first-round playoff series Saturday night at Rocket Mortgage Fieldhouse.

Trade deadline acquisition Josh Hart also had a dynamic game off the bench with 17 points and 10 rebounds (five offensive) in his postseason debut.

And Obi Toppin scored all nine of his points in a pivotal third quarter run for the Knicks, who will look to grab a 2-0 series lead Tuesday in Game 2.

All-Star guard and Westchester product Donovan Mitchell scored a game-high 38 points on 14-for-30 shooting, with Darius Garland adding 17 for the fourth-seeded Cavs.

The Knicks were up by eight points entering the final quarter, and they led 87-77 following Randle’s 3-point bucket with 6:34 remaining.

Mitchell and Brunson — who had missed 10 of the final 14 games with foot and hand ailments — exchanged long-range makes to keep it an eight-point game.

Another Mitchell trey cut the Knicks’ lead to 92-87 with 3:48 to go, and consecutive layups by Mitchell and Cedi Osman off turnovers by RJ Barrett and Brunson trimmed the lead to one.

Jarrett Allen’s tip-in gave Cleveland its first lead since the opening quarter with 2:12 left, but Hart buried a straightaway 3-pointer as the shot clock expired to put the Knicks back up 95-93.

Brunson knocked down two big shots in the final two minutes, and Grimes sank two free throws with 4.1 seconds to go to seal it.

Randle took pregame warm-ups and was reinserted into the lineup after missing the final five games of the regular season with a sprained left ankle suffered March 29 against the Heat.

The Knicks’ lone All-Star buried his initial 3-point attempt and followed that with a driving bucket as the Knicks jumped out to a 9-2 lead.

But the Cavs netted the next nine points, with Brunson sitting down with his second foul just 4:02 into the game.

Randle normally plays the entire first quarter, but Thibodeau altered his usual rotation pattern and subbed out his leading scorer just 40 seconds later, replacing him with Obi Toppin.

Randle returned to the floor with three minutes to go, soon after the Knicks had retaken the lead on a 3-pointer by Grimes and a put-back by Hart.

Randle’s second trey of the quarter boosted the lead to eight, and the Knicks carried a 30-24 advantage into the second quarter.

The Cavs missed seven of eight tries from long distance in the opening period.

The lead was extended to double digits on buckets by Isaiah Hartenstein and Randle in the first minute of the second.

Brunson was removed again after committing his third foul of the half less than three minutes into the session, but Randle’s long 2-point jumper and subsequent layup had the Knicks up by a dozen.

Garland was left wide open for a corner-3 and Mitchell drove the lane to trim the Knicks cushion to seven midway through the quarter.

Randle was fouled by Josh Allen after grabbing an offensive board a few minutes later and then was bumped by Mitchell as he walked away, before raising both arms in the air and appearing to egg on the booing arena crowd with his hands.

Mitchell nailed four consecutive shots to close the gap to five, and he also jumped over the scorer’s table into the seats to save a ball from going out of bounds with 1:28 left. Mitchell finished the half with 18 — two more than Randle — but the Knicks led 50-45 at intermission despite missing 13 of 16 from long distance.

Mitchell Robinson missed an alley-oop dunk and Randle committed a fast-break turnover early in the third, and the Cavs pulled even at 54-all on Mitchell’s triple with 8:12 remaining.

With Randle pulled early again, however, Toppin raced ahead of the field for a one-handed dunk to regain the lead with his first points of the game.

Toppin totaled nine in a 22-11 surge for the Knicks, and Brunson managed 12 in the quarter without committing another foul for a 78-70 lead entering the final period.