2021 Belgrade Challenger

The 2021 Belgrade Challenger was a professional tennis tournament played on clay courts. It was the ninth edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Belgrade, Serbia between 12 and 18 April 2021.

For the first time, a women's tournament was also held between 26 and 31 July, categorized as a WTA 125 event at the same venue, which was part of 2021 WTA 125K series.

Seeds

 * 1 Rankings are as of 5 April 2021.

Other entrants
The following players received wildcards into the singles main draw:
 * 🇷🇸 Peđa Krstin
 * 🇷🇸 Hamad Međedović
 * 🇷🇸 Marko Miladinović

The following players received entry into the singles main draw as special exempts:
 * Gonçalo Oliveira
 * Blaž Rola

The following players received entry from the qualifying draw:
 * 🇩🇪 Matthias Bachinger
 * 🇲🇦 Elliot Benchetrit
 * 🇮🇹 Alessandro Giannessi
 * 🇦🇷 Marco Trungelliti

Seeds

 * 1 Rankings are as of 19 July 2021.

Other entrants
The following players received wildcards into the singles main draw:
 * Tena Lukas
 * 🇷🇸 Lola Radivojević
 * 🇷🇸 Iva Šepa
 * 🇷🇸 Draginja Vuković

The following players received entry from the qualifying draw:
 * 🇫🇷 Jessika Ponchet
 * 🇮🇹 Camilla Rosatello
 * Tara Würth
 * 🇷🇺 Ekaterina Yashina

Withdrawals

 * Before the tournament
 * 🇷🇴 Ana Bogdan → replaced by Tereza Mrdeža
 * 🇮🇹 Elisabetta Cocciaretto → replaced by 🇺🇦 Lesia Tsurenko
 * 🇰🇿 Zarina Diyas → replaced by 🇧🇾 Olga Govortsova
 * 🇫🇷 Océane Dodin → replaced by 🇫🇷 Amandine Hesse
 * 🇮🇹 Sara Errani → replaced by 🇷🇴 Jaqueline Cristian
 * Viktorija Golubic → replaced by 🇸🇰 Rebecca Šramková
 * Polona Hercog → replaced by 🇩🇪 Jule Niemeier
 * 🇷🇺 Anna Kalinskaya → replaced by 🇩🇪 Andrea Petkovic
 * 🇮🇹 Jasmine Paolini → replaced by Jana Fett
 * 🇷🇴 Elena-Gabriela Ruse → replaced by 🇭🇺 Panna Udvardy
 * 🇧🇾 Aliaksandra Sasnovich → replaced by 🇧🇬 Isabella Shinikova
 * 🇷🇴 Patricia Maria Țig → replaced by Susan Bandecchi
 * Stefanie Vögele → replaced by 🇷🇸 Olga Danilović

Seeds

 * 1 Rankings are as of 19 July 2021.

Other entrants
The following pair received a wildcard into the doubles main draw:
 * 🇷🇸 Elena Milovanović / 🇷🇸 Lola Radivojević

Men's singles

 * 🇪🇸 Roberto Carballés Baena def. 🇧🇦 Damir Džumhur 6–4, 7–5.

Women's singles

 * 🇸🇰 Anna Karolína Schmiedlová def. Arantxa Rus 6–3, 6–3

Men's doubles

 * 🇦🇷 Guillermo Durán / 🇦🇷 Andrés Molteni def. 🇧🇦 Tomislav Brkić / 🇷🇸 Nikola Ćaćić 6–4, 6–4.

Women's doubles

 * 🇧🇾 Olga Govortsova / 🇧🇾 Lidziya Marozava def. 🇷🇺 Alena Fomina / 🇷🇺 Ekaterina Yashina 6–2, 6–2