On Wednesday, D.C. United beat that same Chicago team, 2-0, to advance to the championship game of the U.S. Open Cup. In its previous MLS game, United beat third-place Montreal, 3-1.
It should also be noted that United eliminated the Union with a 3-1 Open Cup win on June 12.
Union team manager John Hackworth couldn't have put it in more simple terms when he talked about Saturday's game.
"It's a game we really need to win, and D.C. doesn't need to do that," Hackworth said.
That might make things more difficult for the Union, since D.C. is playing with house money and can be free and loose.
One suggestion: Come out early with everything against a team that played on the road Wednesday and may have some tired legs.
For some reason, the Union can't seem to stand prosperity. They had already beaten Chicago twice this year and had a chance to put a little distance between themselves and the other playoff contenders, but couldn't get it done.
"They had a good game and were desperate for a win," Union defender Sheanon Williams said of Chicago. "Even with that, we had a chance to go up."
Now the Union have little margin for error. They are also fully aware that stopping Dwayne De Rosario will be the No. 1 priority.
In the U.S. Open Cup game, De Rosario, who when healthy is among the top offensive players in MLS, scored all three goals against the Union.
For good measure, he had the game-winner in United's U.S. Open Cup win on Wednesday.
The Union have 11 games left, and each should have a playoff feel. Even if they had beaten Chicago, they would have been far from home free, but would have enjoyed some breathing room.
The Union are approaching Saturday as a must-win game. Even when United weren't playing well the Union struggled in a 3-2 win at Washington on April 21.
Now that United have improved, the Union feel as if they are in a playoff game, even though their opponent won't be in the postseason.
Contact Marc Narducci
at email@example.com. Follow on Twitter @sjnard.