Did you ever have a nightmare that seemed so real it took every fiber of your being to wrench yourself back into consciousness, at which point the relief that it was just a dream washes over you? Then imagine what MLS commissioner Don Garber and the folks at MLS HQ are experiencing right now. Except in their case, there is no waking up from their worst-case MLS Cup playoff scenario.

Inter Miami and its band of stars -- including Lionel Messi -- were eliminated from the postseason by Atlanta United, 3-2; their chance at a Supporters Shield and MLS Cup double turned to dust by a heroic effort on all fronts from the Five Stripes.

In December, there will be no opportunities to party in South Beach, Miami Beach or even Ft. Lauderdale Beach. The chance to attract celebrities to the league's signature event is vastly diminished now that the chances of Messi gracing the event are zero (though if Los Angeles ends up hosting the final that will ease the sting a bit.) And more importantly, the viewership for the rest of the playoffs on Apple TV is bound to take a massive hit given the crater-like hole Miami's elimination has created.

When asked how the Miami locker room was after the match, manager Tata Martino said: "Sad ... as one should be when there are so many expectations, and the team cannot meet them. In this last part of the year we get used to achieving the objectives that we set for ourselves and we have not been able to achieve the most important one."

But honor is due to Atlanta. The Five Stripes were deserving of their win and were by no means intimidated by their opponents. They are now playing with a truckload of house money.

Just how big an "MLSCupset" was this? The fact that the Supporters Shield winners were ousted isn't that unusual in the MLS postseason. Only four teams in the last 20 years have managed to pull off a Shield/MLS Cup double. Upsets are common as well. The bracket in the Eastern Conference has been blown wide open this year, with the second-seeded Columbus Crew and third-seeded FC Cincinnati also eliminated.

That said, Atlanta's triumph is easily the biggest shock in MLS postseason history. The Five Stripes transferred two of its biggest stars -- Thiago Almada and Giorgos Giakoumakis -- in midseason. They then barely squeezed into the playoffs on the last day of the regular season thanks to a 2-1 road win over Orlando -- the opponent in the next round -- combined with the Philadelphia Union and D.C. United both losing. That allowed Atlanta to finish ninth in the 15-team Eastern conference, and a whopping 34 points behind Messi's side. Then Atlanta had to survive a penalty shootout in the play-in round against CF Montreal. They were given next to no chance of getting past Miami, with its cast of stars, and homefield advantage throughout the playoffs.

All seemed to be going according to plan in Game 1, when Miami prevailed 2-1 at home. But Atlanta's 2-1 win at Mercedes-Benz Stadium last Saturday, thanks to a late winner from Xande Silva, kept them alive and then they finished the job in Ft. Lauderdale thanks to a pair of goals from Jamal Thiaré, some stellar goalkeeping from Brad Guzan and a 76th-minute winner from Bartosz Slisz.

All of this was accomplished under the leadership of interim manager Rob Valentino, who in postmatch interviews projected a vibe akin to a young Bob Bradley, complete with a steely visage and bald head. If Atlanta goes in a different direction for its permanent manager, Valentino should make sure his phone is on and fully charged. Given the way he's resurrected Atlanta's season, some team is bound to take interest.

As for Saturday's festivities, how precisely, did Atlanta get this done?

"Grinding, believing, resilience. I don't know," Guzan told Apple TV. "There's some fairydust in our locker room, man. And I couldn't be more proud of our guys."

Valentino added: "You can see the emotion in the players. We've got the ownership there, everybody. There's been some tough times in the club and I'm happy that everybody's getting a little bit of joy. But I hope we're not done now."

Miami is done, and in some respects only have themselves to blame. The team's defense was suspect all season; only once in the last 20 years had a Supporters Shield winner conceded more goals than the 49 goals the Herons let in. (That was Seattle's 50 back in 2014.)

But Miami was usually able to bury teams with an avalanche of creativity, led by the likes of Messi and Luis Suárez. Not this time, despite Matías Rojas putting Miami ahead in the 17th minute, as Thiaré got Atlanta on top with a pair of goals in a span of two minutes, and Miami knew it had a fight on its hands.

There also appeared to be something deeper at work. After claiming an MLS record 74 points in the regular season, the Herons seemed to have difficulty wrapping their collective head around the fact that this, by itself, wasn't enough to be crowned league champion. Instead, it had to go through the hard slog of a postseason. Intuitive to someone from Europe? No. But in MLS it's reality. Miami seemed unable to accept this.

"This format seems a little unfair to me," Miami defender Jordi Alba said. "It is clear that it has been done this way for many years, but if you ask me, I think that if it were up to me, I would have it be the champion of one conference against the champion of the other, to make it as fair as possible."

On the field, Miami's composure began to fray, with Suarez up to his old dark-arts antics. Even when Messi tied the match at 2-2 with a 65th-minute header, Leo Campana shoved goalkeeper Guzan into his own net in the aftermath. Miami was playing on the edge, but Atlanta had no compunctions about engaging in a street fight.

The capper came on Slisz's game winner. With Miami defender Tomás Avilés down with an apparent injury, the rest of the Miami players switched off, thinking that Atlanta or the referee would stop play. -- Martino said afterwards that Miami had done just that during Game 2 in Atlanta -- but that kind of professional courtesy, once common, simply can't be taken for granted these days. The old adage of playing to the whistle was ignored. Atlanta carried on, as is their right, and with Miami's defenders half asleep, Slisz's thumping header from Pedro Amador's cross easily beat Drake Callender.

What bordered on ironic overload was the fact that two of the key architects of Atlanta's win were a pair of lunch-bucket guys, long-time MLS veterans in midfielder Dax McCarty and Guzan. McCarty, who recently announced his intention to retire at the end of this season, assisted on both of Thiaré's goals and ran the show in midfield until fatigue set in at the 60th minute. In fact, Atlanta looked a little wobbly in the minutes after he left the match. Guzan delivered seven saves, some of the spectacular variety that drove Suarez insane. It's a reminder that for all of the star power the likes of Messi and Suarez have brought to the league, winning an MLS Cup still requires some local knowledge as well.

Afterwards, Guzan was hugging everyone in sight; McCarty settled for his two children. Martino and the Miami players were left to rue a missed opportunity.

"The comparison of the last game of last season, back in October with today's third game in the playoffs and this bitterness that we all have for not having passed, is clear that the club's objectives have been modified and I think there is no reason for the club not to continue trying next year," the Miami manager said. "What happened this year, the bad and the good in general have been better than everything that happened last year and I would say even from the [beginning] that the club has."

That is a generous reading of the situation given how Miami fell short in the face of high expectations. There is something else to think about as well: Messi has but one year left on his contract. While he always could extend his deal, the clock is ticking, not only on Messi's time in South Florida, but for the league's ability to capitalize on his presence.

Meanwhile, Atlanta's championship dreams are still very much alive.