The Islanders won’t know until season’s end if the Atlanta Thrashers’ comeback on Saturday night will be the difference in qualifying for the playoffs.

But the Isles still earned the victory despite blowing two separate three-goal leads in a 6-5 shootout win over Atlanta at home.

Ilya Kovalchuk temporarily silenced most of the Nassau Coliseum crowd with a blistering point shot for a power play goal as Atlanta roared back from a 5-2 deficit to tie it almost midway through the final period.

Instead of folding, Jeff Tambellini and Frans Nielsen scored critical shootout goals to send the Islanders into a three-game Western Conference road trip with momentum.

The Islanders entered Sunday tied with Atlanta for the ninth spot at 42 points with the Thrashers playing two fewer games. Despite giving back a point, Josh Bailey said the win was good for the club’s confidence since the Islanders started its game as the NHL’s lowest scoring offense.

“We needed a game like this,” Bailey said. “We haven’t been giving too much support for our goalies lately, so it’s definitely a positive.”

Five regulation goals tied a season-high for the Islanders. The team first accomplished the feat Halloween night against Buffalo.

Even after the scoring barrage, the Islanders ranked second-to-last in goals scored, trailing only Carolina. The Hurricanes claim the league’s worst record and fewest points and has 102 goals compared to 107 for the Isles.

Scott Gordon’s club can make it back to .500, entering Wednesday’s game in Colorado. At 17-18-8, the Islanders will face an Avalanche squad currently occupying first-place in the Northwest Division before venturing to Dallas and Phoenix.

After that stretch of three games in four days, the Islanders head back to the Coliseum to face the defending Western Conference champion Detroit Red Wings Jan. 12. Gordon said his team needs to do a better job of protecting leads should the Islanders surge ahead against the challenging non-conference opponents.

“It’s something you have to learn from,” Gordon said. “You can’t think for a moment that you can take a shortcut or take the easy way out. It’s a lesson learned.”

New York (0-3) rallied from a 23-point early second-half deficit to take a three-point lead in overtime, only to see Philadelphia (2-1) close on a 17-0 run and beat the Knicks 141-127, before a raucous sellout crowd of 19,763 at Madison Square Garden on Saturday night.

For the second time in as many nights, the Knicks dug a huge first quarter hole due to a lack of defensive intensity, stormed back with a big fourth quarter, and eventually lost a heartbreaker after grabbing a lead in an extra session. On Friday night, the Knicks trailed 32-13 after the first quarter in Charlotte, before rallying to lead briefly in overtime, only to lose 102-100.

One night later, New York again allowed an opponent to light up the scoreboard early and often. Philadelphia shot 72.7 percent (16 of 22) from the field, led by four field goals apiece from guard Louis Williams, forward Andre Igoudala, and center Elton Brand, as the 76ers, without attempting a three-point shot, torched the Knicks’ for a 40-25 lead after one quarter. During the period, Philadelphia made all eight of its free throw attempts (five by forward Thaddeus Young) and broke open a 10-10 tie, scoring 12 straight points en route to a larger 22-6 run, to take its biggest lead of the quarter, 32-16, on an Igoudala left wing jumper with 3:20 remaining. The 76ers would match that margin twice more before the first quarter ended.

New York cut Philadelphia’s lead to nine points on three different occasions in the second quarter, the last of which brought the Knicks to within 48-39, with 7:00 left in the half, on a jumper by former 1998 76er first-round pick, forward Larry Hughes (18 points, 7-11 fg, 5 rebounds, 6 assists in 39 minutes off the bench).

The 76ers though, pulled away again, outscoring the Knicks 22-12 over the final seven minutes of the first half, to lead 70-51 at halftime.

At that point, the Knicks were lucky that the hometown fans didn’t egg or toilet paper the court. They headed for the locker room under a chorus boos that weren’t exactly of the variety of Knick fans imitating Halloween ghosts.

Jeers turned to cheers in the second half when the Knicks stormed back and nearly turned the night into a happy “Harroween” or “Galloween” for the Garden faithful, as in Knick forwards Al Harrington and Danilo Gallinari, who each scored career highs to lead New York back. However, that only served to little more than cancel out what the 76ers’ scored in first half.

Harrington finished with a game-high 42 points (30 after halftime) in 36:28 off the bench, making 16 of 23 shots from the floor and 9 of 11 free throws. Replacing Harrington in the opening lineup, Gallinari made his first NBA start with an impressive display from beyond the arc. The second-year, 21-year-old Italian import delighted the crowd, scoring 21 of his 30 points in the second half, finishing 9 of 22 from the field, including 8 of 16 from three-point range, falling just one three-pointer short of the Knicks’ all-time single-game record.

Behind their two leading scorers, the Knicks reversed everything in the second half. They outscored the 76ers by the same 30-26 margin in the third quarter that Philadelphia won the second quarter by, and the Knicks forced the overtime by winning the fourth period, 41-26. Still, just as in Charlotte the night before, they had a big hill to climb, trailing 96-81, entering the fourth quarter.

It seemed as if the game was out of reach when the lead swelled back to 105-87 with 8:59 left in the fourth quarter, and the 76ers still led 110-93 on a pair of free throws by guard Andre Igoudala (team-high 32 pts, 12-21 fg, 11 reb, 8 ast) with 6:52 left in the period.

However, the Knicks, also like the night before, charged back late, as they finally started clamping down defensively and made some stops, while at the other end, Harrington and point guard Chris Duhon (7 pts, 6 ast), who was publicly outspoken about the Knicks not going into Charlotte seriously, both started driving aggressively to the basket.

Harrington scored seven points to during a 15-3 surge which brought New York to within 113-108 with 2:12 left. The last two point of the run came on a pair of Harrington free throws. In between making each one, the draftee out of St. Patrick’s high school in nearby Elizabeth, New Jersey, who always wanted to be a Knick while playing for three other teams over twelve years before arriving in New York last year, stood at the foul line, waving his arms and pulling out the “NEW YORK” on the front of his jersey, exhorting the Garden crowd to roar louder than it already was.

“I was just wanna get ‘em involved,” Harrington said afterwards. “These people pay top dollar to come watch us play. For us to be down 20 and get back in the game, the reason we did that is… we fed off their energy.”

That of course, doesn’t explain the “Defense!” chants from the opening tip during the first quarter, leading to the 76ers’ offensive explosion in that period.

A couple of free throws by forward Thaddeus Young (25 pts, 9-14 fg, 7-8 ft) pushed the 76ers’ lead to 119-112 with just 1:12 left in regulation.

But again, Gallinari and Harrington wouldn’t let the Knicks go quietly.

Two Gallinari free throws made it 119-114, before a jumper by Brand (16 pts, 7-13 fg) increased the lead to 121-114.

Harrington then scored off glass while being bumped in the lane. He made another free throw to complete a three-point play, cutting Philadelphia’s lead to 121-117 with 47.9 seconds left in the quarter. He then rebounded a missed shot by Igoudala which resulted in a Gallinari three-pointer, which sent the crowd into a frenzy and cut the 76ers’ lead to 121-120 with 11.4 seconds left in the period.

A free throw by 76ers’ forward Jason Kapono (6 pts) made it 122-120 with 10.7 seconds to go, before Duhon tied the score, 122-122, on a running, contested layup off glass with 5.9 seconds remaining.

Igoudala raced down the left side, but missed a jumper as time expired in the fourth quarter.

In overtime, Harrington starting the scoring with a three-point play, again taking the ball strong to the hoop, scoring, and making a free throw.

Williams (27 pts, 10-12 fg, 7-8 ft, 10 reb, 7 ast), who played an outstanding game for the 76ers,  answered with a jumper before Harrington made another driving layup to put the Knicks ahead 127-124 with 3:41 left in the game.

But, Harrington fouled forward Marreese Speights (20 pts, 7-10 fg, 6-7 ft, 10 reb), who made two free throws to cut the Knicks’ lead to 127-126, with 3:30 remaining.

More importantly, the Knicks best offensive option of the night fouled out on the play, and Philadelphia completely took over after that. New York wouldn’t score again while Igoudala, Williams, Young, and Speights all scored, usually off of fast breaks, to seal the win over the final three minutes for the 76ers.

“Tough, very tough,” Harrington said on watching from the bench the rest of the way.

On Halloween night, coming back to win from such a big deficit would have been great trick by the Knicks and a real treat for the Garden fans, but without Harrington in overtime, New York simply ran out of gas after a valiant effort.

Although Knicks’ head coach Mike D’Antoni was again displeased with his team’s intensity to start the game, he noted the scrappiness of his tired squad which played three overtimes in two nights. “They could have quit, but they didn’t,” he said. “I just thought in the overtime, we had a complete physical breakdown.”

“We have to find a way to play with a sense of urgency,” Harrington said. “We can’t keep giving teams 20-point leads and then fighting back and then coming in here and feeling good about ourselves… Last year we struggled with our third quarter, this year we struggle with our first quarter. We just gotta find a way to fight through this. There’s no moral victories around here… we’ve got goals we’re trying to accomplish.”

When discussing the slow starts defensively, Gallinari pointed to the need to maintain a consistent effort throughout the entire game. “We have to play our best defense for 48 minutes,” he said. “We cannot allow ourselves to have ups and downs [with that] during the game. Once we keep our energy up, everything goes fine, so we just have to keep our energy at the highest level.”

On the plus side, Gallinari feels no ill effects of the back surgery which kept him from missing most of his rookie season last year. “I feel good, my back is fine,” he said. And, he’s adjusting well to playing in New York. The only time he smiled after the game it seemed, was giving a simple answer on his new home. “Nice city,” he said.

But, Gallinari didn’t feel good about losing. Shrugging aside his own big scoring night, the disappointed and humble forward said, “I don’t feel good. We lost and that’s what matters.”

Two key areas in which the 76ers, who won their second straight, held big advantages were at the free throw line, where they shot 36 of 42 (85.7 percent) compared to the Knicks’ 19 of 24 (79.2 percent), and on the boards where Philadelphia limited New York’s second-chance attempts by outrebounding the Knicks 49-31. Three 76ers were in double figures in rebounds while Harrington and guard Wilson Chandler tied for the Knicks’ lead with just 6 rebounds apiece.

After the game, Knicks’ guard Nate Robinson (8 pts), who sprained his right ankle in the fourth quarter, told Harrington, “We should be 2-1, Bro.”

Harrington nodded in agreement.

Yet instead, the Knicks open a season with three straight losses for the first time since an 0-5 start four years ago, in 2005.

The game kicked off the start of a four-game home stand which will continue with Chris Paul and the New Orleans Hornets on Monday night and culminate with MSG likely buzzing when next year’s free agent Lebron James and his Cleveland Cavaliers visit on Friday night.