NBA

Wounded Knicks return home upbeat

Amar’e Stoudemire plans to suit up in tomorrow’s must-win Game 3 at the Garden. Chauncey Billups may give it a try, too. But neither will be close to 100 percent. The Big Apple 3 has been reduced to the Big Apple 1.75.

With the beat-up Knicks trailing their first-round series to Boston, 2-0, Stoudemire and Billups underwent duel MRI exams yesterday in Manhattan.

Stoudemire was diagnosed with a pulled back muscle resulting from back spasms from Tuesday night’s Game 2. Despite being listed as “day to day,” a person with knowledge of the situation said there’s “a good chance” he will be in uniform and attempt to play through the pain tomorrow. One other source said, “He should be OK,” but there’s no assurances when it comes to the back.

Billups’ MRI confirmed a left knee strain, and he was listed as questionable.

According to a source, Billups’ chances of playing are “50-50.” Billups missed all of Game 2, and the Knicks feel they have suitable backcourt replacements. But they have no replacements for Stoudemire, as Jared Jeffries’ performance against Kevin Garnett in the final 14 seconds proved.

After all, if the Knicks lose Friday and fall behind 3-0, it’s all but over. And it will be a long, bitter summer for Stoudemire after such a tremendous season.

In Game 2, the Big Apple 3 was reduced to the “Only One” — as Carmelo Anthony nearly beat the Celtics by himself in an epic 42-point, 17-rebound, six-assist outing.

The Celtics have looked beatable, and for Knicks fans it’s heartbreaking to imagine what could have been in Boston if the Knicks were at full strength. The Celtics have played ragged and looked scared in the second half after Stoudemire went down for good with back spasms late in the first half, leaving Anthony by himself.

Stoudemire suffered back tightness during pregame warm-ups, on a playful dunk during which he tapped the backboard with one hand while slamming it through with the other.

“Hopefully the next few days it will release,” Stoudemire said after the game.

The Knicks are the last team that can withstand a blow to two of its three top players. The Anthony trade left them thin on the bench, vulnerable to injury. That’s why coach Mike D’Antoni couldn’t be prouder of his team fighting the fight at the TD Garden. By all rights, the Knicks should have been blown out of the building and into the Back Bay. That they took the Celtics down to the final seconds in a 96-93 classic has given them confidence things will be OK at the rowdy Garden — injuries and all.

The Knicks didn’t practice yesterday but Anthony said after Game 2, “The Celtics didn’t do anything special. They won two games on their home court. Now it’s our turn to do the same thing.”

D’Antoni will have to coach his butt off again, like he did in Game 2 in nearly stealing the win.

“I’m proud of them,” D’Antoni said late Tuesday night. “I’m still confident. As they say, it doesn’t start until somebody wins on the other guys’ court. We’ve got to go Friday and I’m sure it’s going to be a great atmosphere. Amar’e should be ready and that right there is going to be all out. I think our heads are high, the locker room is good and they’re confident. I can’t wait until Friday.”

Stoudemire spent all day in Manhattan yesterday getting the MRI and treatment from team therapist David Hancock. Billups had his knee drained and took a cortisone shot. Before he plays on a bad knee, he also has to weigh his long-term health as team president Donnie Walsh still can decide against exercising the $14 million option on the final year of his contract.

That would seem unlikely, because Toney Douglas does not look ready to inherit the point guard position. He couldn’t keep up with Rajon Rondo, who exploded on the fastbreak, scored on 11 layups and finished with 30 points, tying his playoff career high. Douglas’ shooting was erratic — 5-of-16.

Even if Anthony and his minions were outclassed talent-wise, they played scrappier than the Celtics and outrebounded them 20-9 on the offensive glass.

“We see how far we got with everybody we had,” said Bill Walker, who shot 0-for-11 in Game 2. “We can build on this and get those guys back, build up some steam and get two at home.”

The Knicks, without a playoff win since 2001, are 0-6 against the Celtics this season. They need to win four of the next five.

marc.berman@nypost.com