Atlanta United owner Arthur Blank’s message was simple to his team’s supporters ahead of the MLS Cup at Mercedes-Benz Stadium on Dec. 8:

“Welcome to Atlanta and welcome to the MLS Cup.”

The message was delivered on Twitter after the team dispatched the New York Red Bulls 3-1 in a two-game series that ended in the cold of Harrison, N.J. The victory assured that Atlanta United, in just its second season, will play for its first title.

Confetti fell from the sky as Atlanta United players danced around the field. Captain Michael Parkhurst grabbed the trophy, looked over his shoulder at his teammates behind him, and then lifted the silver cup over his head as the call-and-response echoes of “Atlanta,” “United” could be still be felt from the team’s travelling supporters.

Multiply those few hundred fans, who held their own against the Red Bulls’ supporters on the end of the pitch, by a few thousand to imagine what Mercedes-Benz Stadium will sound and feel like when the players for Atlanta United and Portland march out of the tunnel and onto the turf in eight days.

“I can’t even imagine because I feel like I have said it after a lot of games that is just keeps on getting louder and louder in our stadium, and the last game against the Red Bulls was the loudest by far that I have ever seen Atlanta, and I expect it to be even louder for the MLS Cup game,” Atlanta United captain Michael Parkhurst said. “They just keep outdoing themselves. Our support is amazing. I know that there was a lot of fans back home in Atlanta getting together for that game, so thank you for your support, we can’t wait to play in front of you next weekend.”

Support that has broken numerous single-game, playoff game, U.S. Open Cup and average league attendance records has helped carry Atlanta United to a 22-5-7 record at its two home venues – Bobby Dodd Stadium and Mercedes-Benz Stadium – in the past two years.

In the playoffs, the supporters created two of the more interesting tifos in league history. The first was a tribute to outgoing manager Gerardo Martino before beating NYCFC 3-1 in the second leg of the semifinals. The second was a stadium-wide display of red, gold and black shiny pieces of paper help up people in the stands. The coordination and choreography rivaled tifos of long-standing clubs in Europe. Atlanta United went on to defeat Red Bulls 3-0 in that game to set up Thursday’s game and the foregone conclusion that was the team advancing to the MLS Cup, despite the 1-0 loss.

That support will be amplified by the hundreds to thousands of Portland fans that are expected to make the cross-country trek to root on their team. Portland also is expected to bring The Big Log, which gets a piece chopped off after every Timbers goal.

“Postgame interview I said to one of my friends in Texas, California, wherever you are, the house is going be open,” Atlanta United fullback Greg Garza said. “Just can’t wait for what the city will have to bring. The last game against Red Bulls at home was unbelievable, everyone involved, so I think we’re hoping for something like that again.”

Manager Gerardo Martino smiled Thursday as he talked about his memories of his introductory news conference at the World of Coca-Cola in September 2016.

He said he understands very little English now. He knew even less then. A man who has coached the national teams of Paraguay and Argentina and club powerhouse Barcelona was very nervous as journalists with recorders and cameras peppered him with questions that were translated.

The Argentine then went to work in an office in Arthur Blank’s Foundation building, writing down on a white board the names of potential players that he hoped could be signed.

As the team was constructed, shed some players and then was re-constructed for this a title run this season, the supporters continued coalescing into various groups: Terminus Legion, Footie Mob, Resurgence and Faction. Each with their own goal and culture.

With the groups as the core, the casual fans continued to come to games. Some were soccer fans, in general. Some grew up playing the game, inspired by the Chiefs, Generals and Silverbacks. Some just heard attending a game can be a good time.

Attendance records fell like the Red Bulls players who tried to draw fouls Thursday. A new league record average attendance of 48,200 last season. A record 53,002 this season. Including the MLS Cup, the team will sell and distribute more than 1.1 million tickets this season.

Most of those fans embraced Martino. They embraced the players. They embraced the faces of the front office, president Darren Eales and vice president Carlos Bocanegra. The supporters came for any question and answer, or any meet-and-greet at pubs during the grassroots marketing campaign sessions before the team had a name or kit, and only a few players.

They came to Compound when the team name was announced.

They came to Tabernacle when the red-and-black kit that inspired the Five Stripes nickname was unveiled.

They traveled to Chattanooga for the first exhibition game.

They traveled to Nashville for the first exhibition game of the second season.

They were everywhere during the week of the All-Star game against Juventus during the summer.

They traveled to New Jersey to see their team add another chapter to its short history.

Some congregated near Gate 46 of the Newark airport Friday, rehashing the game and talking about their team’s chances in the MLS Cup before flying home.

And they are expected to turn the MLS Cup at Mercedes-Benz Stadium into a must-attend event, with Blank saying hello as Martino says goodbye. It will be his last game as the club’s manager. It may also the last game for several players, including MVP candidate Miguel Almiron, who is presumed to be sold to a team in England or Europe during the winter transfer window.

“…It will be a chance for us to say good-bye to them,” Martino said. “Regardless of the score, it's been important to play in front of those people.”