Toronto FC celebrates Nicolas Benezet’s goal. (Brett Davis-USA TODAY Sports)

ATLANTA — Ladies and gentlemen, get ready for Toronto FC vs. Seattle Sounders FC, Round 3.

Toronto FC overcame an early one goal deficit and stunned defending MLS Cup champion Atlanta United on Nick DeLeon’s 24-yard wonder strike in the 78th minute en route to a 2-1 upset triumph in the Eastern Conference semifinals at Mercedes-Benz Stadium Wednesday night.

The win boosted Toronto FC into MLS Cup as it will meet Seattle Sounders FC in Seattle Sunday, Nov. 11 for the third time in four years for Major League Soccer supremacy. The teams split their confrontations, both played in Toronto. Seattle won the first encounter in a shootout in 2016 before Toronto captured the 2017 title match.

It was the second upset in as many nights by the underdog visiting team. On Tuesday night, Seattle surprised Supporters Shield champion Los Angeles Football Club in Los Angeles in the Western Conference semifinals, 2-1.

“I would have to say today was resiliency,” Toronto head coach Greg Vanney said. “It was not beautiful soccer. The guys refused to give up. … Passion, heart, dedication and just making saves.”

Added captain Michael Bradley: “Look, you have to know how to win differently on different days. The mentality, the commitment, just the sheer determination from all the guys, when things didn’t come easily was truly special.”

DeLeon, who came on for first-half goal-scorer Nicolas Benezet in the 54th minute, scored his fifth lifetime playoff goal. He had the ball outside of the box, did a pirouette and launched a line drive into the upper left corner past goalkeeper Brad Guzan to snap a 1-1 deadlock.

“My intent initially was to hit it first time,” DeLeon said. “It wasn’t the best angle. I improvised a little. It was fortunate to go in.”

DeLeon, whose 11th-hour goal eliminated the Red Bulls from the 2012 playoffs, admitted it has been difficult not playing regular and coming off the bench.

“I’m not going to lie. It’s been tough,” he said before praising the team. “Me and other guys, we’re committed. We’re committed as a group. Credit goes to the guys who kept us in the game. Team effort. Gutsy win.”

Some observers might say that Atlanta lost the game as much as Toronto won it give what transpired in the opening half.

Atlanta dominated huge portions of the game, but could not find the back of the net when it counted.

“Disappointing,” said Atlanta defender Michael Parkhurst, who played his final professional game. “We started out the game so well. We could have been winning 2-0. We weren’t crisp enough up front. We created half chances. We needed to be more precise in the final third.”

The hosts got off to a rousing start, connecting for a fourth-minute goal. Ezequiel Barco fed Pity Martinez with a long ball down the left flank and the Argentine bolted in on goal on a 2-on-1 break with Julian Gressel on his right. As he bore down on goalkeeper Eric Westberg, Martinez slotted a pass to Gressel, who slotted in home for a 1-0 lead.

Minutes later, Atlanta threatened to double its advantage after Toronto FC captain Michael Bradley knocked down Martinez near the penalty spot for a penalty in the eighth minute.

Josef Martinez took the ensuing penalty but got off a soft shot that Westberg dove to his right to easily save and keep the game from getting out of hand in the 11th minute.

“It was kind of a sham PK,” Vanney said. “Great save.”

“To know you have a goalkeeper to make big plays to keep you in the game is invaluable,” Bradley said. “He was excellent tonight.”

Atlanta struggled to get its mojo back for the rest of the opening half.

Only three minutes later, the momentum changed dramatically when Toronto FC equalized off Benezet’s 19-yard goal against the run of play past goalkeeper Brad Guzan.