Time: 4:00 p.m. EDT
Venue: PPL Park, Chester, Pa.
TV: WPVI-6 (J.P. Dellacamera, Alejandro Moreno and Heather Mitts, with Tony Limarzi, Peter Pappas and Ian Munro at the on-site studio desk)
Seattle's start to the season has been perhaps the most disappointing in Major League Soccer. But that makes this game something of a trap for the Union, because the Sounders still are loaded with quality attacking players.
How will the Union respond? I have a hard time believing that John Hackworth will alter his starting lineup much from what we've seen in recent weeks.
But since it's May the 4th, let's quote that famous former manager of Rebel Alliance FC:
Do or do not. There is no try.
In addition to live updates from PPL Park, I'll pull in tweets from the two other MLS games going on at the same time: Columbus-New York and San Jose-Montréal.
If you're on a mobile device, click here to follow along.
Philadelphia Union (4-1-3-2, left to right)
Goalkeeper: Zac MacMath
Defenders: Raymon Gaddis, Jeff Parke, Amobi Okugo, Sheanon Williams
Midfielders: Brian Carroll; Michael Farfan, Keon Daniel, Danny Cruz
Forwards: Conor Casey, Jack McInerney
Bench: GK Chris Konopka; D Gabriel Farfan; Ms Kléberson, Michael Lahoud; Fs Antoine Hoppenot, Sébastien Le Toux, Aaron Wheeler
Seattle Sounders (4-1-3-2, left to right)
Goalkeeper: Michael Gspurning
Defenders: Leo Gonzalez, Djimi Traoré, Jhon Kennedy Hurtado, DeAndre Yedlin
Midfielders: Servando Carrasco; Alex Caskey, Brad Evans, Mauro Rosales
Forwards: Lamar Neagle, Eddie Johnson
Bench: GK Marcus Hahnemann; Ds Patrick Ianni, Zach Scott, Eriq Zavaleta; Ms Mario Martínez, Andy Rose; F David Estrada