ATLANTA – Minnesota United plays Tuesday for the biggest prize in its short history, on Major League Soccer's biggest stage. The Loons will do so before a Mercedes-Benz Stadium crowd that could surpass 50,000 people, almost all of them cheering their Atlanta United on toward winning its first Lamar Hunt U.S. Open Cup.

At stake is $300,000, a coveted trophy contested by U.S. amateur and pro teams alike since 1914 and a place in the Americas' Champions League competition come February.

There are no three points to gain in a league playoff race tightening by the week and still it is the most important game played yet in the Loons' three MLS seasons because it's for a cup, if one step down from the MLS Cup won by the league's annual champion. Last season, that MLS Cup winner was Atlanta United, Tuesday's opponent and a team that is best in the Eastern Conference and 10-1-3 at home this season.

A Minnesota team that travels by commercial airliner the rest of the season chartered a jet to Atlanta for itself and its office staff and another for its supporters in a traveling party that all told could reach 500 people. Goalkeeper Bobby Shuttleworth was recalled from the USL so he could share in the moment. The Loons themselves stayed in a five-star hotel, befitting the NBA lifestyle.

The match will be shown on the ESPN+ pay service and broadcast on AM1500 radio.

"It's important," said coach Adrian Heath, who won one F.A. Cup final in England and lost two when he played. "We're a new club in the grand scheme of things. I think it's something for everybody to enjoy, for everybody to come and sample what it's like. The emotions you have winning semifinals and going all the way, the memories you have with your teammates, that's something I still remember now 30, 40 years on.

"It's important everyone is here and realizes the importance of the game."

Sanctioned by the U.S. Soccer Federation, the knockout tournament played out over months — and its final, too — are played by rules different from MLS: There are no video reviews and each team can field only five international players each game. If the game is tied, two 15-minute overtime periods will be played. The final will be decided by penalty kicks after all that, if needed.

Loons captain Ozzie Alonso first played in a U.S. Open Cup final in 2008, one year after he walked away from a Houston Walmart and his Cuban national team to a new life that included playing that first year for a minor-league team in Charleston, S.C.

He helped lead the Charleston Battery to the Open Cup final that season against MLS's D.C. United. He stepped into the big leagues the next season, signing with a Seattle Sounders team that reached the Open Cup final in 2009 and four of the next five seasons.

He'll play in yet another Tuesday, having won three consecutive Open Cups nearly a decade ago and four of his six overall. Teammate Ike Opara won two with Sporting Kansas City.

"This is my seventh final, and I'm happy to be here one more time," said Alonso, 33. "Any trophy means a lot for any player. So many play in their career and never win anything. I want to tell my teammates to enjoy the game. You never know if you're going to get another opportunity. For me, it's special because I don't know if it's going to be the last one."

Minnesota United and Atlanta United both entered the MLS in 2017 as expansion franchises, but took divergent directions to Tuesday's final, which is a first for both teams.

Atlanta has played its way this season into hosting at Mercedes-Benz Stadium, where Minnesota United won late in its first season despite Atlanta's overwhelming home-field advantage.

"I'd prefer it to be at Allianz," Heath said. "But, hey, it's a great venue. We've spoken to the players about when you're a kid growing up, certainly in America, your parents drive you hours and hours all over the country. All those days in the back of the car and on aeroplanes, this is what that was for. If you don't enjoy this, you're probably in the wrong sport."