Eleven years ago, with the San Jose Earthquakes on the verge of leaving the Bay Area, a handful of devotees joined forces to try to save their beloved team. They formed the Soccer Silicon Valley advocacy group that worked with local politicians and potential investors to lobby to stop the move.

Now those who fought vigorously for a local professional team feel a sense of elation on the eve of Sunday’s first regular-season game at privately financed, $100 million Avaya Stadium, considered by some to be one of the country’s best soccer facilities.

“There is a sense of vindication as fans,” said Don Gagliardi, a San Jose lawyer who was among the original organizers in 2004. “We were right all along: This was a team worth caring about it.”

Sunday’s Major League Soccer game against the Chicago Fire at the 18,000-seat stadium has been sold out for weeks. The Earthquakes have created a waiting list after selling their allotment of 12,000 season tickets as they build a regionwide fan base to become more than a niche sport.

For everyone involved, it starts with Avaya Stadium, located next to Mineta San Jose International Airport on Coleman Avenue.

The first MLS Quakes — originally named the Clash — played at San Jose State’s Spartan Stadium from 1996 to 2005, then moved to Houston because of a lack of a permanent home. For the past seven years, the next iteration of the team played at 10,500-seat Buck Shaw Stadium at Santa Clara University.

It has taken perseverance and patience for fans to see the day the Quakes would call something other than a college campus their field.

Avaya Stadium had a successful soft launch three weeks ago in an exhibition match limited to 10,000 fans.

“It felt like coming home,” said Colin McCarthy, a San Jose lawyer who founded Soccer Silicon Valley.

“You were there with all the people who fought with you back then.”

It was more like an open house for San Jose’s Tony Huston, one of those who helped McCarthy. “This is the real end to the game,” he said of Sunday’s match.

The “game” began with McCarthy, who says, “I’ve always fought for stuff I believed in.”

When rumors of the team’s imminent departure circulated in 2004, McCarthy, Gagliardi and their cohorts gathered at a local watering hole to develop a plan to stop the move of a team that had won two MLS titles in the previous four years.

At the time, Anschutz Entertainment Group owned the Earthquakes, the Los Angeles Galaxy and some other MLS teams. Fans said their voices were not being represented.

The owners and league officials treated the Earthquakes as if “it’s theirs and they can do what they want with it — end of story,” said Vallejo’s Jay Hipps, another influential fan.

Hipps understood his brethren didn’t have a financial stake in the team, “but we had a lot invested in it in our time and emotions,” he said.

For more than a year, Soccer Silicon Valley mobilized forces through social media. The men organized a rally in 2004 in downtown San Jose where an estimated 1,500 fans showed league officials the team had support.

Their efforts bought them time. The Earthquakes remained in San Jose for the 2005 season, a year they had the league’s best overall record.

Finding a permanent place to play, however, proved too steep a challenge to overcome. AEG moved the team to Texas and called it the Houston Dynamo.

While local fans lost their team, they saved the brand. Gagliardi, McCarthy and company persuaded MLS officials to keep the Earthquakes’ name, team colors and records for a future club.

Mike Turco, who plans to attend the game Sunday although he now lives in North Carolina, said saving the brand was important.

“It is so identified with this team,” said Turco, who was part of the Soccer Silicon Valley group.

When Oakland Athletics owners John Fisher and Lew Wolff revived the Quakes in 2008 as an expansion team, they floated the idea of re-branding it FC San Jose. But the core fan group talked them into keeping the Earthquakes’ name.

The biggest issue, though, was the stadium. The owners, who also are trying to solve a stadium issue with their baseball team, knew the Earthquakes needed a soccer-specific home to survive.

“When we brought the team back we wanted to do something special,” Fisher said.

MLS teams, like other pro sports franchises, use stadium revenues to help offset the rising costs of players’ salaries. The Earthquakes are the 15th of 20 Major League Soccer teams to have their own stadium.

According to reports, Fisher and Wolff paid $20 million to join MLS eight years ago. Current expansion team New York City FC paid $100 million, Forbes reported.

As soccer has gained a toehold across the United States, the half-dozen Earthquakes supporters feel pride in a mission that at times seemed fruitless.

“It was never a matter of if we can do it, but it was a matter of how we could do it,” said Huston, who played soccer at Monta Vista High-Cupertino.

Hipps, who owns a graphics company in Vallejo, recalled feeling unsure if Soccer Silicon Valley was pushing a good investment or a community service.

“It turns out we had a heck of an offer to make for people,” he said.

Contact Elliott Almond at 408-920-5865. Follow him on Twitter at twitter.com/elliottalmond.