Based on the Tournament Format for the 2004 Lamar Hunt U.S. Open Cup, there will be eight (8) qualification slots for the ten (10) U.S.-based A-League teams. All Primary Qualifiers and the top Secondary Qualifier enter in the Third Round. The two remaining Secondary Qualifiers enter in the Second Round.
The primary qualifiers will be the winners of a two-leg, aggregate goal series predetermined by geography. If the score is tied after the two matches, penalty kicks will determine which teams advance. Those matches are: