NBA

Shaky Knicks fail to put away Celtics

The Knicks and J.R. Smith said this series was over, but somebody forgot to tell the Celtics.

In nothing short of a choke, the shaky Knicks allowed the Celtics to keep their season alive and take Game 5 in a 92-86 shocker Wednesday night at the Garden, staving off a so-called “funeral’’ for Boston.

The Knicks appeared to get too full of themselves in the past few days and it cost them. Smith bragged the series would be over if he played Sunday.

Following the lead of Kenyon Martin, several of the Knicks players had black jackets and black slacks hanging in their lockers before the game, pretending they were attending the Celtics’ funeral.

After Game 4, Martin said he would wear black Wednesday after Jason Terry told him Sunday he wouldn’t let the Knicks dance at their funeral. Martin did and his teammates did too in a presumptuous move for a franchise that hasn’t won a playoff series since 2000.

“We were going to a funeral, but it looks like we got buried,” J.R. Smith said.

The Knicks still lead the series 3-2, but it’s headed back to Boston, echoing memories of 2004 when the Red Sox rallied from a 3-0 deficit to trounce the Yankees. No NBA team has recovered from a 3-0 series deficit.

There was shoving after the final buzzer — typical of the bad blood between the teams — but no blows were thrown. Raymond Felton had to be restrained.

Smith, back from a one-game suspension, was not the returning hero but the goat as he missed his first 10 shots in a horrendous outing and probably knows Jason Terry’s name now. Smith scored 14 points — including a last-second 3-pointer when the game already was decided — and finished a woeful 3-for-14 from the field.

Carmelo Anthony hurt his left shoulder early in the fourth quarter and labored through a 8 of 24 performance. Anthony was 2 of 10 in the second half.

When Jeff Green rolled to the hoop for a driving dunk with 8:00 left, the Celtics led 75-60 and the Garden became stone-cold silent. Kevin Garnett and Paul Pierce each scored 16 points and Terry banged in 17.

The Knicks offense collapsed without the spark from Smith or Anthony. They shot 5 of 22 from 3-point range — their bread and butter.

Smith didn’t make his first field goal until there was 2:47 left — on a 3-pointer from the left wing. He made his next 3 to bring the Knicks to within 88-83 with 1:05 left, but it was too late. Garnett iced it with a 20-footer, faking Tyson Chandler, to get the lead back to 90-83 with 48.3 seconds to go.

Smith got a standing ovation when he checked in with 6:38 left in the first quarter after serving his controversial one-game suspension for elbowing Terry. But Smith looked to be pressing and bricked his first four shots. He was a minus-8 in the first quarter, going 0-for-4, and finished the half at 0-for-5 with three free-throw makes. He also was a minus-8 for the game.

The Knicks looked primed to blow Boston out of the building in taking an 11-0 lead before stunningly falling to pieces. The Celtics got back into it in a big way and took a 45-39 at halftime, capped by a Terry 3-pointer with 26.6 seconds left.

A Pierce 3-pointer gave Boston its first lead at 34-33 with 5:34 left in the first half. The Celtics maintained the lead as Pierce hit Garnett for an alley-oop as Anthony and Smith fell asleep in transition.

The Knicks shot 41 percent in the half and made just 1 of 6 3-pointers, not at all resembling their sharpshooting ways.

Anthony entered the final quarter at 6 of 18. He was 0-for-4 with two points in the third quarter and the Celtics took a 69-60 lead into the fourth quarter.

Smith was 0-for-5 by halftime and couldn’t drop a J in the third quarter either, going 0-for-3. At one point, Smith let an easy bounce pass slip through his fingers out of bounds. He also appeared to be a step slow on defense.

The Knicks were in foul trouble with Martin picking up his third early in the second quarter on a hard foul on Garnett, who went flying. It was originally called a flagrant 1 but was reduced to just a personal foul.

Chandler picked up his third in the final minute of the half, forcing Woodson to dust off 7-1 Marcus Camby,

marc.berman@nypost.com