There's a new love in town, sports fans.

Michelle Stella grew up with season tickets to the Eagles, and hasn't missed a home game in 10 years. But the Union, a soccer team in only its second season, have their first-ever MLS Cup playoff game, against the Houston Dynamo, on Sunday.

Turns out, the Union play in the afternoon, and the Eagles play the Dallas Cowboys at night, so Stella's boyfriend will rush her from one game to the next. But when she thought she had to choose - there was no choice.

"When I found out the playoff game was the same day as the Eagles-Cowboys game, I said, 'Well, I'm going to the soccer game,' " Stella said. "I would never have dreamed of missing an Eagles game, much less an Eagles-Cowboys game. But this is my team. This is my family, at this point. The atmosphere is so different from any other sport I've ever been to."

Stella, 23, a middle-school math teacher from Souderton, will be among 3,000 fans who stand at the river end of PPL Park, the soccer stadium in Chester, and sing and cheer and chant and scream and dance for 90 minutes straight, without a rest. They are known as the Sons of Ben, and the group's early support was a critical reason the expansion club came to the Philadelphia area in the first place.

But the Union's first playoff game, in just its second season, is a milestone worth noting. The team's success, on and off the field, proves that the region will not only support professional soccer, but also embrace it with the passion and devotion it showers on the Eagles, Phillies, Flyers, and 76ers.

The facts speak for themselves. Fourteen of 18 home games were sold out, with 18,000 fans attending, and executives are already talking about expanding the stadium. Television ratings doubled from the first season to the second, from 35,000 households to 70,000 per game - still relatively small, but striking growth.

And perhaps the best symbol of the team's acceptance among hardcore Philly sports fans is that sports talk radio WIP - home for years to much soccer-bashing - will broadcast 17 Union games next season.

"That's a huge culture shift," said Matt Ansbro, of Hatboro, 40, a father of four, youth soccer coach, and president of the Sons of Ben.

Ansbro works for Apple computers. He's an otherwise smart and sensible man. But he will stand the whole game, mostly with his back to the action, leading the faithful in song and chant.

"It's pretty neat to see the city come together and embrace not just the team, but the entire culture of the sport," he said.

"There was a lot of rolling eyeballs when I first came to town," said Nick Sakiewicz, the Union's CEO. " 'Yeah, you're going to build a stadium? And where - in Chester? And it's soccer?' "

But if Sakiewicz had any doubts about fan support, they vanished in 2008.

Two days before Sakiewicz was to announce that he and partners were buying the new franchise, he called Bryan James, the founding president of the Sons of Ben, to tell him the news, and thank him for all the work the group had done lobbying Major League Soccer and politicians to put a team in Philadelphia.

Sakiewicz wanted to buy James a beer at the Dark Horse Pub on South Street.

James asked if he could bring all the guys involved.

"I thought it was 30 or 40 people," said Sakiewicz. "I show up, and there are maybe 750 at the door. And the bar tab was $4,000. But it was the best $4,000 I ever spent. Truly galvanized in my mind what a great soccer market this is."

A large number of Union fans have a background in soccer, as former players or youth coaches, but many are like Stella, the math teacher and Eagles fan. She never played soccer and was just a sports fan who rounded up friends to go to the first game last season and see what it was like.

"From the first game, the first kick, I just knew," she said.

Unlike in other sports, there is no music pumped into the stadium. Fans must provide all the noise.

"We're loud and we're crazy and we feel like our job is to be there and help the team win," said Stella, a section leader now with the Sons of Ben. "It's almost like work. It's a job. I go home and pass out and I'm so tired. And I would do it every day if I could.

"I lose my voice and I go through packs of cough drops," she added, "and I go to school and I'm so tired, but this is my life. And my students are always asking me what doop is and I love telling them about it and the people I've met."

Every Union fan knows and understands the meaning of doop. It's an "all-purpose word," explained Lucas Murray, 30, a fan from Fishtown. Doop, he said, can be noun, verb or adjective, an expletive or an exclamation. It can have any meaning a person wants.

For example, Murray broke up with his girlfriend, but said he's not looking for love at Union games. "I try not to diddle where I doop," he explained.

Doop came into existence as a cheesy techno song - "a song you might hear at a rave," Murray said - and fans of a few European teams started singing it after their teams scored a goal.

Union team manager Peter Nowak suggested local fans consider singing the "doop song" after Union goals. Soon, doop became ubiquitous in Union culture.

The fan experience in many ways can be much more interactive than in other sports.

Nowak and his players have come to fan tailgates before and after games. Injured player Veljko Paunovic sat with the 1,200 fans who went to the last regular-season game, against the New York Red Bulls.

After home games the team will bow before the Sons of Ben and applaud fans for their support.

The Union finished their first season in last place, but with a combination of young and seasoned players they finished third this year, earning Sunday's first-round playoff game against Houston.

The week leading up to Sunday's game has been a celebration, a chance to appreciate the team's progress.

"They've done a terrific job for a new team," said Bob Zwengler, 57, of Haddonfield, who coached youth soccer, grew to love the game, and never misses a game. "From the stadium, which is a great place to see a match, to bringing in a top management team and world-class coach, to continually seeking to improve the quality of personnel. They've established a great connection with fans from the start.

"Clearly, Philly was ready for this."