In the MLS, it's very important to earn the top three spots in the conference and earn a first-round bye, avoiding a single-elimination game between the fourth and fifth place teams.
Chicago plays host to D.C. United at 4 p.m. on Saturday, so those teams will know New York's outcome.
The Red Bulls must beat the Union to have a chance at either second or third. And if New York and Chicago are tied, the Red Bulls should earn the edge based on the first tiebreaker - goals scored. (New York currently has 54 goals, nine more than Chicago.)
If Chicago beats the United and New York defeats the Union, both the Red Bulls and United would have 57 points. New York has scored two more goals than United.
If New York wins and United wins while also scoring two more goals than the Red Bulls, more tiebreakers would be needed. So this is a must-win for New York and a chance for the Union to be a spoiler against its biggest rival.
Players on the Union are fighting for spots for next season and a strong showing in the season finale will give team manager John Hackworth and the players something to build on.
Plus, the Union had won three of four before losing their last two games, at Houston on Saturday and at Sporting Kansas City on Wednesday.
Wednesday's 2-1 loss at K.C. was the Union's 12th one-goal defeat this season.
That doesn't mean they are close to being a playoff team, but it shows how slight the margin of error is in MLS.
Despite their record, the Union have competed hard and remained competitive, and while they didn't envision themselves as spoilers when the season began, it's their only way to leave a favorable final impression on an otherwise disappointing season.
Contact Marc Narducci at firstname.lastname@example.org, or follow on Twitter @sjnard.