Sixteen-year-old Upper Dublin, Pa., native Zach Pfeffer has been handed his first ever start for the Union tonight, and it comes in one of the club's biggest games of the year.
The Union, who are stuck in a logjam in third place in the Eastern Conference, need a win tonight over the first-place Columbus Crew in order to keep pace in the race for a bye to the second round of the MLS Cup playoffs.
Pfeffer was signed to the senior Union squad last year as the club's first ever "homegrown" player. He has played for U.S. youth national teams at the under-14 and under-15 level, and has particiated in the U.S. Soccer Federation's under-17 residency program at the IMG academy in Bradenton, Fla.
Tonight's lineups in full are below. As you'll see, Pfeffer definitely isn't the only young Union player in the squad tonight. Peter Nowak has also moved Michael Farfan to the forward line for the first time, pairing him with Sébastien Le Toux.
New signing Morgan Langley is on the bench, after joining the club just hours before MLS' roster freeze deadline.
Among the missing veterans are midfielders Velkjo Paunović, who has a strained left calf, and Justin Mapp, who has a strained left quadriceps.
Columbus is also missing some of its stalwarts. Midfielder Emmanuel Ekpo is suspended due to a red card in the Crew's last game; defender Chad Marshall is out due to a hip injury suffered in that game game; and forward Emilio Renteria is out due to a concussion suffered in a collision with Toronto FC goalkeeper Stefan Frei on September 10.
You can get live game updates in the console below the lineups. If you're on a mobile device, you can follow along by clicking here.
Philadelphia Union (4-4-2)
Goalkeeper: Zac MacMath
Defenders: Gabriel Farfan, Danny Califf, Carlos Valdés, Sheanon Williams
Midfielders: Brian Carroll, Freddy Adu, Roger Torres, Zach Pfeffer
Forwards: Sébastien Le Toux, Michael Farfan
Bench: GK Thorne Holder; Ms Morgan Langley, Stefani Miglioranzi, Kyle Nakazawa, Amobi Okugo; Fs Jack McInerney, Danny Mwanga
Columbus Crew (4-4-2)
Goalkeeper: Will Hesmer
Defenders: Sebastian Miranda, Julius James, Shaun Francis, Eric Gehrig
Midfielders: Danny O'Rourke, Dejan Rusmir, Dilly Duka, Robbie Rogers
Forwards: Tommy Heinemann, Andres Mendoza
Bench: GK Chris Konupka; D Josh Williams; Ms Josh Gardner, Cole Grossman; Fs Jeff Cunningham, Aaron Horton, Justin Meram