It’s a semifinal at home. That is your reason: Go watch!
Normally, this is where a list of the best reasons to tune in to the upcoming Union game would appear, but… this is a semifinal. That is enough.
Additionally, the Union should be favored at home against a weaker opponent. They will boast a healthy lineup and a 2-0-0 record against the Fire this season. Meanwhile, Chicago is dealing with a season-long rash of injuries and an ever-changing tactical setup that tends to devolve into confusion around their box. That is not to say this will be an easy win, but it will be a contest the Union should control, and they should create chances throughout the match.