It was a historic achievement for New York City FC, who reached the semifinals of the Concacaf Champions League for the first time in club history Tuesday night in Guatemala City.

But it was also nearly an epic late collapse that saw the Cityzens concede three unanswered goals in the final 21 minutes of a second half that provided important lessons following a 4-2 second leg defeat to Comunicaciones.

“I think it was a really good learning lesson for how to act in these kind of games when you need to defend and suffer and get through things,” NYCFC head coach Ronny Deila said. “We did things that we should have done better, but we learned something without getting any consequences and that's really good.”

The aggregate series finished level at 5-5, but NYCFC advanced on the away goals tiebreaker. The current MLS Cup champions will now face either Seattle Sounders FC or Club Leon in the semifinals.

It was the slimmest of margins, but it didn’t look that way in the opening hour, with NYCFC leading 2-1 on the night, and 5-2 on aggregate, following Talles Magno’s 53rd-minute goal. That gave Deila a chance to rest some weary legs after what he said was a “perfectly executed” game plan for 60 minutes. He went with a quartet of changes on the hour mark, with Maxi Moralez and Taty Castellanos, who opened the scoring with a free kick golazo in the 31st minute, among those to leave the match.

What followed was an onslaught from Comunicaciones, who scored twice in a span of three minutes and then leveled the series two minutes from full time.

“In the end, we got scared. You have to be more brave in this kind of situations,” Deila said. “As I said, there was a young team and I'm very, very happy that we get that kind of experience without getting any consequences out of it.”

When the final whistle blew, there were no celebrations in the visitor’s dressing room at Estadio Nacional Mateo Flores. Just a realization a bullet was dodged and they very much survived and advanced.

“It's hard to celebrate. If you were there in a changing room, it was very quiet because we are all professionals and even if we get qualification losing the game, we never get happy about that,” defender Maxime Chanot said. “I think it’s going to give us a little bit [of a] good lesson. Maybe a bit more humility for the next leg.”