I take it the game is in Chicago? How many USL and Mls teams are in the cup?
Open Cup is in tiers. USL is Tier 3, despite NASL in Tier 2 not being much better (if at all).
The first round is all Tier 4 teams. Winner of Tier 4 plays a Tier 3 team.
Winners of tier 3 plays a Tier 2 team. Louisville beat Tier 2 Indy Eleven in the third round.
The fourth round is really when the tournament starts where the first 3 rounds are play-in games to make it. There are still 32 teams in the tournament in Round 4.
Game is in Chicago.