The New York Red Bulls will have a chance to win their first MLS Cup title after a 1-0 win at Orlando City on Saturday in the Eastern Conference final.
A 47th-minute header from Andres Reyes gave the Red Bulls the victory and a place in the December 7 final.
The New Jersey club will face the winner of Saturday's Western Conference final between Los Angeles Galaxy and Seattle Sounders.
The Red Bulls qualified for the playoffs with a seventh place in the regular season, earning them the final automatic spot in the playoffs.
Sandro Schwarz's team then pulled off a major upset by beating defending champions Columbus Crew in the best-of-three first round before eliminating local rivals New York City last week.
Orlando had the early pressure and Red Bulls keeper Carlos Coronel had to be at his best to keep out an effort from Facundo Torres after a counter-attack.
But Red Bulls threatened themselves when their Swedish playmaker Emil Forsberg floated a free-kick into the box and Belgian Dante Vanzeir flicked the ball just wide.
Two minutes after the interval, New York grabbed the decisive goal when John Tolkin's free-kick was delivered perfectly to the back post, where Reyes arrived to head in.
Orlando grew increasingly desperate in their attacks -- Duncan McGuire got round the back of the Red Bulls defence but fired his shot well wide and then Luis Muriel's rushed effort from a promising position flew harmlessly off-target.
The last chance of the game fell to Ivan Angulo but he too failed to find the target as the Red Bulls, founding members of MLS in 1996, held firm.
"I'm very proud of the whole group. It's amazing to create this atmosphere and also with this fighting spirit. Amazing the last couple of weeks and now we have one week more and it's not done," said New York coach Sandro Schwarz, a German who was the former Mainz and Hertha Berlin coach.