ATLANTA, GA -- At the start of the Major League Soccer playoffs, Toronto FC and the Seattle Sounders were not supposed to reach MLS Cup. Even two days ago, they still weren't the favorites. But on Tuesday night, Seattle stunned LAFC 3-1, winning the Western Conference. A day later, TFC, visitors at Atlanta United's Mercedes-Benz Stadium fortress, matched that feat by beating the 2018 cup champions 2-1 courtesy of substitute Nick DeLeon's 78th minute goal.

For Toronto -- who will meet Seattle in a rematch of the 2016 and 2017 MLS Cup on Nov. 10 (3 p.m. ET on ABC) -- the up and down tilt resembled their up and down season.

"If you look at the whole year, I think the night was a microcosm," head coach Greg Vanney said post-game. "Early in the year we battled.

"We went into midseason trying to keep our head above water, got our team back together, and we've been on a run.

"Tonight, look, it was similar. We were missing a couple guys [like Jozy Altidore and Omar Gonzalez], but the guys who were out there battled.

"I don't think anyone outside of our club, our fans, and us thought we could get it done."

In the early going, however, the home side looked unstoppable.

While it took Atlanta United more than half the 2019 MLS season to find their form, it took less than three and a half minutes for manager Frank de Boer's team to prove they could ball in front of Wednesday night's crowd of 44,055. Their opening tally came when Ezequiel Barco, transferred into the club for a reported $15 million before the 2018 season, hit a through-ball to Pity Martinez -- this year's $14 million acquisition -- who slid the ball across to Julian Gressel for a tap in. The pace, the creativity, the joy were all vintage Atlanta United, a callback to last season's Miguel Almiron-Josef Martinez goalfest.

It was been a weird year for United, as well. They lost talisman Almiron to Newcastle and head coach Tata Martino to the Mexico national team before the season started. Ajax-schooled De Boer joined, bringing with him a more disciplined system. Early results in the CONCACAF Champions League were terrible, and while United won five straight in April and May, and eight of 11, the team was limping along.

They got back on track a bit in July, although defender Leandro Gonzalez Pirez spoke out at the All-Star break, saying: "We're working to return to the way it was before and how we characterized through and differentiated us apart from other teams. We're returning to that a little bit, you're seeing a new face to the club, now we have to continue working on that to fortify that."

They did, more or less, earning the second seed in the Eastern Conference and the third seed overall.

Despite Wednesday's loss, De Boer sounded pleased with the progress his group made in 2019.

"We struggled in the beginning [of the season] when to play compact and when to play aggressive forward, one against one," he said. "We did that much better today. To see how Pity played. That's how you want your No. 10 to play.

"When we had the ball, he was every time too fast for [Toronto's Michael] Bradley."

After the early goal, Atlanta should have doubled their lead in the 11th minute, but Quentin Westberg saved Josef Martinez's penalty kick after Pity Martinez -- by far the best player in the opening 45 -- drew a foul from Bradley.

"It's instinct," the goalie said of the save. "I was well prepared. J.C., my goalkeeper coach, obviously had all the PKs from the opposing team.

"I didn't make a choice. I studied them, but in the end I figured it would be instinct."

Two minutes later, Toronto FC drew level on a curling Nicolas Benezet effort off a long crossfield pass from Laurent Ciman. Half-time came and went, and TFC just kept hanging around. Atlanta controlled the play, winning possession 59.5 percent to 40.5 percent and outshooting the visitors 18 to 4 on the night. It didn't matter.

"You can't be the most talented team all the time," Westberg said. "Sometimes the brave team and the strong tam and the resilient team wins."

His coach agreed.

"Sometimes, for myself, I can be ideological about how I want the game to look and how I want the team to play," Vanney said. "From an ideological perspective, that's not how I wanted the game to look like, obviously. But from a practical perspective and what our players did today, they deserved it. And that's real.

"But from a soccer perspective, we probably didn't win very many categories, except for one: 2-1 on the scoreboard."

Which is another way of saying that the point of playoff soccer is to win however you can, ugly if you have to, even if you boast MLS's highest payroll as TFC does.

DeLeon's winner, his fifth career postseason goal, came seemingly out of nowhere, one of those half chances that was true.

"[Alejandro Pozuelo] played it across," DeLeon said while drinking a beer in the locker room after the match. "I intended to hit it first time but it was a little off so I improvised a little. Turned and nobody stepped. I decided to have a go. And fortunately it went in."

He said that it was his favorite goal "so far." Pozuelo admitted he didn't think it was going to go in but then added: "He shoots amazing so I can't say nothing."

Roughly 20 minutes later, referee Alan Kelly blew the final whistle. Pity Martinez and Barco collapsed onto the turf, backs to the ground, eyes facing up at the closed roof. Toronto's subs ran toward the middle of the field where their teammates were celebrating.

"It was a group effort," DeLeon said. "It definitely wasn't the prettiest in the second half but we stuck it out. We got the result.

"We got one more to go. We're going to enjoy this one probably tonight and tomorrow. And we'll focus on Seattle."