2021 Thoreau Tennis Open

The 2021 Thoreau Tennis Open was a professional tennis tournament played on outdoor hard courts. It was the second edition of the tournament which is part of the 2021 WTA 125K series. The tournament had been upgraded from ITF 60K to WTA 125K, marking its first edition as a challenger event. It took place in Concord, United States between 2 and 8 August 2021. The tournament could not be staged in 2020 due to COVID-19 pandemic.

Seeds

 * 1 Rankings are as of 26 July 2021.

Other entrants
The following players received wildcards into the singles main draw:
 * 🇺🇸 Alycia Parks
 * 🇺🇸 Katrina Scott
 * Lulu Sun
 * 🇺🇸 Sophia Whittle

The following player received entry using a protected ranking:
 * 🇨🇦 Rebecca Marino

The following players received entry from the qualifying draw:
 * 🇺🇸 Robin Anderson
 * Mariam Bolkvadze
 * 🇺🇸 Victoria Duval
 * Liang En-shuo

The following player received entry as a lucky loser:
 * 🇺🇸 Alexa Glatch

Withdrawals

 * Before the tournament
 * 🇫🇷 Clara Burel → replaced by 🇨🇦 Rebecca Marino
 * 🇷🇺 Vitalia Diatchenko → replaced by 🇧🇷 Beatriz Haddad Maia
 * 🇷🇺 Anastasia Gasanova → replaced by 🇩🇪 Tatjana Maria
 * 🇯🇵 Nao Hibino → replaced by 🇯🇵 Kurumi Nara
 * 🇪🇸 Nuria Párrizas Díaz → replaced by 🇺🇸 Usue Maitane Arconada
 * 🇧🇪 Alison Van Uytvanck → replaced by 🇺🇸 Alexa Glatch

Seeds

 * 1 Rankings are as of 26 July 2021.

Other entrants
The following pair received a wildcard into the doubles main draw:
 * 🇺🇸 Brittany Collens / 🇺🇸 Victoria Hu

Withdrawals

 * Before the tournament
 * 🇮🇳 Ankita Raina / 🇬🇧 Eden Silva → replaced by 🇩🇪 Mona Barthel / 🇮🇳 Ankita Raina

Singles

 * 🇵🇱 Magdalena Fręch def. 🇲🇽 Renata Zarazúa 6–3, 7–6(7–4)

Doubles

 * 🇹🇭 Peangtarn Plipuech / Jessy Rompies def. 🇺🇸 Usue Maitane Arconada / 🇪🇸 Cristina Bucșa 3–6, 7–6(7–5), [10–8]