The path to the MLS Cup will go through Philadelphia after the Union wrapped up the Supporters' Shield and top seed for the Eastern Conference playoffs on the final day of the MLS regular season on Sunday.
The Union got goals from Sergio Santos and Cory Burke to beat New England 2-0 and claim the Supporters' Shield for the first time in club history. It's the first major trophy for the Union in their 11th MLS season.
"On paper, we're probably not the most talented or the team that people would pick at the beginning of the year. But that's what makes pro sports special," coach Jim Curtain said. "A group of guys that have belief, that have confidence. They get better every day and they're in a good environment. It's a special group that we have and again, I couldn't be more proud of the players."
Out West, Sporting Kansas City withstood a snowy, sloppy field in Utah for a 2-0 victory over Real Salt Lake and claimed the top seed in the Western Conference. Sporting KC got goals from Khiry Shelton and Erik Hurtado early in the second half to secure home-field advantage.
The single-elimination MLS Cup playoffs will get started on Nov. 20 following an upcoming break on the FIFA calendar for international matches. Sporting KC will open with No. 8 seed San Jose.
"It was amazing on the field. There was just nothing you could do. We couldn't even play all that well, but we found the way," Sporting KC coach Peter Vermes said. "Again, it was big for us, it's big for the club, it's big for the city. Home-field advantage is obviously much more important when you do have your full stadium, but having some fans is really big."
The snowy victory for Kansas City was part of a wild final day in the Western Conference, with late goals in Los Angeles and Houston shuffling the playoff bracket.
LAFC, last year's Supporters' Shield winners, surrendered a late equalizer in a 1-1 draw with Portland that dropped the Timbers to the No. 3 seed in the West. Combined with Colorado's 93rd-minute goal from Diego Rubio for a 2-1 victory over Houston, the Rapids vaulted into fifth in the West and LAFC fell to the No. 7 seed.
LAFC's reward is a trip to defending MLS Cup champion Seattle in a rematch of last year's Western Conference final won by the Sounders on the road. Seattle, the No. 2 seed, closed the season with a 4-1 win over San Jose.
"You got to go beat the best if you want to be the best," Seattle coach Brian Schmetzer said. "Obviously LAFC is going to have revenge on their mind and they're going to want to come up here and do what we did to them down there. It's going to be a very spirited game."
The other matchups in the first-round in the West have No. 3 seed Portland hosting No. 6 seed FC Dallas and fourth-seeded Minnesota United hosting No. 5 seed Colorado.
Only Philadelphia and Toronto had a chance to lay claim to the regular-season title entering the final day of the season. But the Union held all tiebreakers with Toronto as long as they won.
Toronto ended up with the No. 2 seed in the East despite a 2-1 loss to the New York Red Bulls.
The Eastern Conference had a logjam at the bottom of the standings, and the final day ended with both expansion teams claiming playoff spots.
Nashville had already clinched a postseason berth, but it will have a home match for the play-in round after scoring twice in the final minutes to claim a 3-2 win over Orlando City. Fellow expansion side Inter Miami beat FC Cincinnati 2-1 and claimed the final playoff spot in the East after Chicago lost 4-3 to NYCFC.
One of those expansion sides is guaranteed of advancing, with Nashville hosting Inter Miami. In the other play-in round match, No. 8 seed New England will host ninth-seeded Montreal. The Impact beat D.C. United 3-2 to claim a postseason spot.
The loss to Nashville plus Columbus' 2-1 win over Atlanta United dropped Orlando City to fourth in the final standings. Orlando City will now face No. 5 seed NYCFC in the opening round. The other Eastern Conference matchup is No. 3 seed Columbus facing No. 6 seed New York Red Bulls.