On a rainy Saturday in maybe the slipperiest month in the annals of A-T-L sports, the city's lone reigning champ had reason to tread lightly. No, Atlanta United isn't the Braves, who just gave us 10-0 after a half-inning, and the Falcons, who haven't won since Sept. 15, but the soccer club is still an Atlanta team, if you get my drift.

In its first postseason match since winning the MLS Cup in December, Atlanta United's opponent was New England, an unassuming No. 7 seed. (In the revamped MLS playoffs, there are no No. 8 seeds.) When last these teams had met, which was 13 days ago, Atlanta United won 3-1. When they played in April, it won 2-nil, a result memorable because that was the first league game – there'd been four already -- under coach Frank de Boer that the defending titlists won.

For a while, it was touch-and-go whether de Boer would last longer here than at Inter Milan (sacked after 14 matches) and London’s Crystal Palace (sacked after five). But his new club hit its stride in May and kept going. The new man mightn’t be a fast starter, but he’s no fool. It would have taken a dolt to make a hash of this team.

Atlanta United won a couple of domestic cups – soccer is nothing if not a cornucopia of  cups – en route to finishing second in the East, which is where the club finished last season. Atlanta United blew through five playoff games without much stress, but the new format means that stress is just a 1-0 deficit away. No more two-leg ties. Everything is a one-game knockout.

Atlanta United forward Hector Villalba (15) heads the ball over New England Revolution midfielder Brandon Bye (15) in the second half during the first round of the MLS playoffs at Mercedes-Benz Stadium on Saturday, October 19, 2019. Atlanta United won 1-0 over the New England Revolution. (Hyosub Shin / Hyosub.Shin@ajc.com)

Credit: HYOSUB SHIN / AJC

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Credit: HYOSUB SHIN / AJC

In what we call American football, the better team usually wins. (Except, er, when Georgia plays South Carolina.) In the world's brand of football, there aren't many massive upsets. Mediocrities up and win on a weekly basis. This first half ended with Atlanta United having had 57 percent of the ball but half as many shots on goal as New England. The hosts were demonstrably the more skilled side, but every soccer match comes down to who scores and who doesn't.

Atlanta United’s best early chance fell to Josef Martinez, who doesn’t flub many chances. This one he did. After chesting down Justin Meram’s corner, the famous scorer had time and space. His shot cleared the crossbar. The visitors then put Atlanta United goalkeeper Brad Guzan to work. Teal Bunbury hit a hard shot off a counter-attack that Guzan caught. Cristian Penilla struck a harder one. Guzan batted it aside.

The first 45 minutes ended scoreless, which suited the No. 7 seed fine. A road underdog will settle for penalty kicks after 30 minutes of added time, a fate that undid Atlanta United in the inaugural playoff run of 2017. This match was beginning to recall that fizzle until the 70th minute, whereupon a goal changed it.

The Revolution failed to clear a ball in the box. Ezequiel Barco, for whom Atlanta United paid $15 million as a teenager, dribbled sideways and sent a lovely pass to charging Franco Escobar, charging down the right flank. His shot, which beat Matt Turner from a tight angle, was worthy of any striker. The sight of the ball rippling the net prompted a roar from the usual massive crowd – let’s see if Arthur Blank’s Falcons fill as much of Mercedes-Benz Stadium on Sunday as his soccer team did Saturday – that was equal parts joy and relief.

A note about Escobar: He’d started the match as one of three central defenders, de Boer having opened with a 3-4-2-1. He changed to a back four, with Escobar scooting over to right fullback, in the 65th minute. Who said this coach wasn’t flexible in his tactics? (Back in the spring, more than a few did. This correspondent, ahem, might have been among them.)

Said de Boer: “After 15 minutes (of the second half), we didn’t have the same control we’d had. I tried to change the system, and it helped.”

The final seconds were frantic. With Atlanta United down a man after captain Michael Parkhurst was forced to leave with a shoulder injury, the last act was a Revolution header off a corner that arced over Guzman’s crossbar. As the ball landed behind the net, the whistle blew for full time.

Goals change games. Some goals change seasons. Escobar’s goal lifted Atlanta United to Thursday’s conference semifinal. Three more wins and there’ll be another trophy in the case that, as of January 2017, didn’t exist. You know this already, but the way this franchise keeps moving from strength to strength has been astonishing.

“We’re a team that loves these types of games,” de Boer said, and it showed. Denied early, United kept playing. The Atlanta United coach thought of something. A redeployed central defender scored the winner. It’s almost as if this isn’t an Atlanta team at all.