What happened Sunday at Talen Energy Stadium seemed, in many ways, impossible.

It seemed impossible at halftime, when the New York Red Bulls led the Union, 3-1, having scored the third just seconds before the whistle.

It must have seemed impossible for the many Comcast subscribers across the Philadelphia area who couldn’t watch the game after the region’s dominant cable provider lost Fox Sports 1’s broadcast until the final seconds.

Above all, it felt impossible for most of the Union’s 10-year history of failures and calamities.

But it really did happen. The Union won a playoff game for the first time ever, 4-3 in extra time, with Marco Fabián, the team’s biggest ever star, scoring the winning goal.

The Union were in a 1-0 hole within six minutes, and a 2-0 hole within 24. Alejandro Bedoya got one back in the 30th, and momentum turned in the Union’s favor. But in the final seconds of the first half, Andre Blake collided with Mark McKenzie chasing a ball in the air, and Tom Barlow put it in.

While almost everyone else figured there was no way back, the Union refused to give up. Jack Elliott scored in the 52nd, and suddenly the game was very much alive. Shots flew toward both nets, and in between, plenty of tackles flew, too.

Then, in the 78th, with rain pouring down and the crowd as loud as it’s ever been for a sport that’s finally gaining mainstream acceptance here, Fafa Picault rose above a crowd to head in the equalizer.

At that point, there had to be another goal — especially when New York brought its veteran scoring ace, Bradley Wright-Phillips, in off the bench. Both teams’ fans in attendance figured he might soon score a winner.

Instead, the goal came from the only player on the field with more star power.

Fabián entered in the 103rd minute, two minutes shy of the end of the first extra time. As the period ticked into its own stoppage time, Ilsinho, Jamiro Monteiro, and Picault teamed up for a pretty passing sequence down the right flank. Picault crossed the ball over the 6-yard box, and Fabián collected it, unmarked.

Here was the Mexican star’s big chance to prove to all his doubters — some of whom were in the stands Sunday — that he was worth the $2 million price tag, the Union’s biggest ever.

As Fabián cut away from the end line, two Red Bulls defenders closed in on him. Fabián shot anyway, and the ball hit Marc Rzatkowski, then floated high up, and back down.

For most of the last 10 years, that ball probably would have gone out of play. This time, it fell onto the far post and bounced into the net.

The Union now head to Atlanta to face defending champion Atlanta United on Thursday at Mercedes-Benz Stadium (8 p.m., ESPN2 and ESPN Deportes).

“We have 12 different countries [in] a very diverse locker room, but everybody's on the same page fighting for the same thing,” said Jim Curtin, who goes in the history books as the first Union manager to win a playoff game just a few months after fans booed him in his own stadium.

“Before this game, I said we have to win,” he said, and indeed, he had said it repeatedly. “At 2-0 down, I was regretting all the things I had maybe said, and maybe put too much pressure on our guys.”

By the end, he could barely contain his joy.

Los Angeles Galaxy 2, Minnesota 1

Sebastian Lletget and Jonathan dos Santos scored four minutes apart midway through the second half, leading the Los Angeles Galaxy to a 2-1 victory over Minnesota in the first round of the MLS playoffs Sunday night to spoil United’s postseason debut.

The Galaxy will face crosstown rival Los Angeles FC in the second round in the first ever playoff game between the two teams.

MLS playoffs conference semifinals schedule

Eastern Conference

Wednesday, Oct. 23: E1. New York City FC vs. E4. Toronto FC at Citi Field, New York, 7 p.m. (Fox Sports 1, Fox Deportes)

Thursday, Oct. 24: E2. Atlanta United vs. E3. Philadelphia Union at Mercedes-Benz Stadium, Atlanta, 8 p.m. (ESPN2, ESPN Deportes)

Western Conference

Wednesday, Oct. 23: W2. Seattle Sounders vs. W3. Real Salt Lake at CenturyLink Field, Seattle, 10 p.m. (Fox Sports 1, Fox Deportes)

Thursday, Oct. 24: W1. Los Angeles FC vs. W5. Los Angeles Galaxy at Banc of California Stadium, Los Angeles, 10;30 p.m. (ESPN, ESPN Deportes)