Atlanta United is one win way from a chance to defend its MLS Cup.

A goal from Julian Gressel with an assist by Pity Martinez in the first half and another goal by Josef Martinez with an assist by Gressel in the second half were enough for the Five Stripes to unequivocally defeat Philadelphia 2-0 on Thursday in the Eastern Conference semifinal playoff game at Mercedes-Benz Stadium.

Atlanta United will host Toronto, which knocked off top-seeded NYCFC, at 8 p.m. Wednesday in the conference final. The winner will advance to play for the MLS Cup on Nov. 10.

“It was important that we put together a performance to build off the game against the New England,” Atlanta United goalkeeper Brad Guzan said. “Understanding what had happened last night and the opportunity that presented itself, we knew it was a fantastic chance to take care of business tonight and host the conference title, so it is a massive win.”

With many in the announced attendance of 41,507 wearing cardboard crowns, the Five Stripes defense had it their way with a second consecutive shutout in the playoffs this season and sixth in eight playoff games in franchise history. This one came with the team down to its last healthy centerbacks.

Manager Frank de Boer made three changes from the lineup that helped Atlanta United defeat New England 1-0 in the first round of the playoffs. The first was expected: Flo Pogba in for the injured Michael Parkhurst (shoulder). The next two weren’t: Mikey Ambrose, who has two starts for first team in league games since mid-April, in for Justin Meram, whose form had dipped in recent games, and Pity Martinez in for Emerson Hyndman. De Boer said last week that he thought Hyndman was part of a three-man midfield that had good balance. Pity Martinez hadn’t played a minute in the previous two games. The rest of the lineup, playing out of a 4-3-3 formation, which was one more change: goalkeeper Guzan, centerback Leandro Gonzalez Pirez, right fullback Franco Escobar, defensive midfielders Jeff Larentowicz and Darlington Nagbe, right midfielder Gressel, left midfielder Ezequiel Barco and striker Josef Martinez.

“For me, today was the right moment to play this system with these players,” de Boer said. “As I always have said to you guys and to my players before, I always choose the players who have the most chance to win this game. It’s the best team, not always the best players. Tonight, this was the best team to win against Philadelphia.”

De Boer said he chose to play four at the back because of Philadelphia’s style, which included a diamond-shaped midfield. He started Pity Martinez to try put pressure on Haris Medunjanin. The ploy worked. Medunjanin didn’t create a chance in the first half. He finished with two.

“I’m going to be here when the coach needs me,” Pity Martinez said. “I’m 100 percent ready to play, after that it’s the coach’s decision if I play or not. Today, I showed that I’m still playing well. I’m happy that we’re going to another final, that’s not a small feat. This is what the team is looking for, to keep growing, keep breaking records, and maintain a winning mentality.”

And Atlanta United took advantage of Medunjanin’s weakness on defense for its first goal when Pity Martinez passed around him before playing Gressel into space. Gressel said he was surprised that goalkeeper Andre Blake came out of his goal so quickly. He said he had two choices: either a chip, or try to play it by him and hope for a foul and penalty kick. He went with the chip from 16 yards. The shot touched the underside of the crossbar in the 10th minute. It was Gressel’s seventh goal and Martinez’s 10th assist.

Philadelphia began to crank up its pressure, perhaps remembering that it twice rallied from two-goal deficits to eliminate the New York Red Bulls in the first round.

Guzan kept Atlanta United ahead by one in the 17th minute when he rushed out of his goal to stop Brenden Aaronson in a one-on-one. The shot came from a counterattack and pass by Sergio Santos from the left toward the top of the penalty box. The counterattack started when an Atlanta United shot was blocked, which sent the ball all the way to midfield.

Atlanta United held on to finish the half with the lead and began to take control of the game in the second.

A late stop by Raymon Gaddis prevented Josef Martinez from giving Atlanta United a 2-0 lead in the 69th minute. He was played in by Pity Martinez, who hit a nice chipped pass.

De Boer brought on Hyndman for Barco in the 73rd minute.

Josef Martinez’s header went wide in the 79th minute after a back-post cross by Gressel.

De Boer used his second sub to continue shoring up the defense with Eric Remedi on for Pity Martinez in the 80th minute.

But it was Atlanta United which struck next with Josef Martinez roofing a left-footed shot past Andre Blake and into the upper left corner. Martinez outran two defenders to catch up to a long pass from Gressel, who said he saw Martinez coming back to him, which is a signal that he’s about to turn and run into space behind the defense. Centerback Mark McKenzie misplayed the ball, allowing Gressel to catch up to the ball. It was an impossibly difficult shot from an impossibly difficult angle. Larentowicz said he almost fell over when the shot went in.

“I can’t be happy when I miss three goals,” Martinez said. “I missed the easiest chances and the difficult ones I’m able to score, but I’m happy with the victory. The team suffered and played very well – better than the last game. We have to be happy now because we’ve got another final at home. The next game I hope to not miss as many.”

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