The Knicks were without three of their best players, including Carmelo Anthony. No matter. It seems any ragtag bunch can beat the Heat these days.

Defensive laziness and disinterest defeated the Heat on Tuesday in Washington. On Thursday, the three-point shot did in the defending champions at AmericanAirlines Arena. The Heat allowed 18 three-pointers in a 112-92 loss to the Knicks, who are 2-0 against Miami this season.

Steve Novak drilled a three-pointer with 6:18 left in the game to put the Knicks (14-4) ahead 100-84. Novak wasn’t done. He nailed another triple following a breakaway dunk by J.R. Smith and then stepped inside the line to give the Knicks a 19-point lead.

Miami played poorly the entire game, but in the end the Heat (12-5) simply gave up.

Knicks fans, and there were plenty, stood and cheered as New York poured it on. Heat coach Erik Spoelstra had to call a timeout with 3:47 left and his team down by 21 points to limit the bloodletting. It didn’t help. Smith nailed a three-pointer out of the timeout.

“This game was played like a shootout but in the wrong direction for us,” Spoelstra said.

It was another embarrassing game for the Heat, which lost to the NBA’s worst team, the Wizards, on Tuesday. Thursday’s blowout to the rival Knicks was more troubling, though. Spoelstra started and played injured players to keep up with the Knicks, who were without Anthony, a pregame scratch.

Even with Anthony, the Knicks wouldn’t have been anywhere near full strength, with Amare Stoudemire and Iman Shumpert still out with injuries.

Sharpshooting more than made up for the injured players. The Knicks went 18 of 44 from three-point range to hand the Heat its first home loss of the season. It was also the first time this season the Heat was held to fewer than 100 points at AmericanAirlines Arena.

After the game, Spoelstra told his team in the locker room it would “stay connected … own it … and fix it.”

LeBron James fell one assist shy of a triple-double. He had 31 points, 10 rebounds and nine assists, but it wasn’t enough to make up for off nights by Chris Bosh and Dwyane Wade. Bosh and Wade combined to go 6 of 25 from the field for 25 points.

“We’ve got to come together and talk this thing out to climb out of this hole,” Bosh said.

Raymond Felton outplayed Wade at shooting guard, going 10 of 20 from the field and 6 of 10 from three-point range. Novak had 18 points off the bench, shooting 7 of 13 from the field and 4 of 9 from three-point range.

In two games this season, the Knicks are 37 of 80 from three-point range against the Heat. New York was 19 of 36 from distance in the first meeting between the teams in New York.

“They pretty much kicked our [butt] the last two games,” James said.

The Knicks led by 10 points to begin the final period and extended it to 13 when Jason Kidd started the quarter with a three-pointer. It was the Knicks’ 15th three-pointer of the game. Kidd finished with 11 points, and center Tyson Chandler had 13 points and nine rebounds while shutting down Bosh in the paint.

A 13-2 run put the Knicks ahead by 18 points with 3:06 left in the third quarter. Felton, James White and Smith buried back-to-back-to-back three-pointers during the spurt. It gave the Knicks eight three-pointers in 12 attempts in the third quarter. New York was 6 of 17 from three-point range in the first half.

Many of the Knicks’ three-pointers came on wide-open looks. Spoelstra contributed the poor perimeter defense to a lack of concentration and poor overall effort.

“We need to address our defense and commit to it and do it harder … and then we’ll start to change,” Spoelstra said. “That’s where we are right now.”

For the game, the Heat went 6 of 16 from three-point range. Ray Allen was 0 of 3 from long distance. Shane Battier, who returned to action after missing three games with a knee injury, did not score and committed four fouls in nine minutes off the bench.

Anthony’s pregame scratch because of a lacerated finger was a surprise but not as big of a shocker as Udonis Haslem receiving his first start of the season and then scoring 10 points in the first half. Haslem entered the game with 25 points on the season but scored the Heat’s first four points, including a dunk to start the game.

Haslem played 16 minutes in the first half and was 5 of 5 from the field with five rebounds. He didn’t score in the second half.