NBA

J.R. takes blame after Knicks lose, fall in 3-1 series hole

Carmelo Anthony (right) and Tyson Chandler walk off the court during a timeout in the second half of last night’s Game 4 loss to the Pacers. (Charles Wenzelberg/New York Post)

INDIANAPOLIS — Carmelo Anthony spoke in a whisper. J.R. Smith took blame for this collapse. Tyson Chandler had no criticism, just praise for the Pacers. Mike Woodson seemed stunned their shotmaking has gone so wayward, so quickly.

The Knicks have sunk in a deep hole, a series deficit from which the franchise never has recovered. The Knicks offense has collapsed — along with their once-promising season. Their first second-round appearance in 13 years is turning into a nightmare.

The Pacers routed the Knicks, 93-82, at Bankers Life Fieldhouse to jack their second-round series lead to 3-1. The Knicks never have rallied from a 3-1 deficit — just eight NBA teams have in history.

“I take the blame for this whole series,” Smith said. “I’ve been letting my teammates down, I’ve been letting my coaches down, and it doesn’t feel good.”

Smith, still playing with the remnants of the flu, shot 7-for-22 for 19 points to extend his miserable slump. In six games since his suspension for an elbow in the first round, he is 26-of- 91.

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“I believe, I really believe we can to do something special,’’ Anthony said in a low voice. “We must win [tomorrow] and we got to believe in ourselves. At this point, it’s do or die. No need to hang heads at this. We got to do it being very confident.’’

It took Anthony all the effort he can muster to try to remain optimistic. Game 5 is at the Garden tomorrow, where the Knicks season may end against the tall, burly Pacers.

“We got to put these [past] two games behind us,’’ Woodson said. “We have an uphill climb. It’s still doable. I can’t lose hope.’’

Anthony scored 24 points but went scoreless in the fourth quarter and fouled out with 2:00 left battling for an offensive rebound. Anthony, who shot 9-for-23 after going 0-for-4 in the final period, can’t get enough help as the Knicks were plagued with fouls and couldn’t compete on the boards again. The Knicks shot just 36 percent.

“I thought our offensive flow wasn’t bad but we couldn’t make shots,’’ Woodson said. “We got to find guys who could put the ball in the hole.’’

The Pacers’ size and strength have proven too much. Woodson started with a big starting lineup, adding Kenyon Martin at power forward, moving Anthony to small forward, but it didn’t help.

Indiana slaughtered the Knicks, 54-36, on the boards to continue a series-long trend. The Pacers collected 16 offensive rebounds, leading to 19 second-chance points.

“They’re pinning their ears — five guys crashing the boards,’’ Chandler said. “For the defense after making the stop, it’s a backbreaker.’’

Chandler and Anthony cleared the air over Chandler’s critical comments about the selfish offense. Anthony claims he wasn’t offended.

“I didn’t take it like he was throwing a jab at me,’’ Anthony said. “Our offense has been [crummy]. We haven’t been effective.’’

Pacers 7-foot-2 center Roy Hibbert wasn’t an offensive threat but rebounded terrifically, collecting 11, with three blocks. Hibbert again was a force in the middle stopping the Knicks’ penetrations.

“The way they play defense, the bigs sit back in the paint,’’ said Anthony, who picked up his fifth foul midway through the fourth and lost his mojo. “We have to have confidence in taking the shots we normally take and make. We’re passing up on open shots. We have to take those shots and be confident taking those shots and knowing you can make them.’’

Jason Kidd went scoreless for the eighth straight game, going a hesitant 0-for-2 in 15:46. He even blew a breakaway layup and was seen chuckling on the Knicks bench. Kidd took away minutes from the benched Pablo Prigioni, who had started since late March.

Amar’e Stoudemire played 11 nondescript minutes in the second game of his comeback, picking up four fouls and four points.

“We haven’t played well since Game 3 in Boston,’’ Kidd said. “We have to just let it fly. Stay tough, stay positive.’’

The ball moved. The ball didn’t go in.

“It’s frustrating to talk about our offense and not being able to score the basketball with the weapons we have,’’ Anthony said.

The greaseboard in the locker room read afterward: “Stay the Course. Win one, change everything.’’

Easier said than done.

marc.berman@nypost.com