The 2021 Lamar Hunt U.S. Open Cup tournament proper was to feature teams from all five tiers of the men's American soccer pyramid.
Qualification for the 2021 tournament was drastically altered due to the ongoing COVID-19 pandemic. The tournament itself was downsized to 16 teams, before ultimately being canceled for the second consecutive season due to the pandemic.
The top eight American-based teams based in the regular season standings after three weeks of the season, taken on a points-per-game (PPG) basis, were set to qualify for the tournament before its cancellation. Qualification began on April 16, 2021, and concluded on May 2, 2021.
The four semifinalists from the USL Championship playoffs qualified. Qualification retroactively began on October 10, 2020, and ended on October 17, 2020.
Phoenix Rising qualify
El Paso Locomotive qualify
Louisville City qualify
Tampa Bay Rowdies qualify
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The NISA Fall Champion, Detroit City FC, retroactively qualified on October 2, 2020.
The 2020 USL League One champion, Greenville Triumph SC qualified.
The game was canceled the day before because several Union Omaha players tested positive for COVID-19. Greenville was awarded the title based on points per game average (2.188 to 1.825), and reached the Open Cup.
Two slots will be selected from the Open Divisions:
<br> The draw awarded the slots to Newtown Pride FC (NAC) and FC Golden State Force (USL2).