2021 Lošinj Open

The 2021 Lošinj Open was a professional tennis tournament played on clay courts. It was the first edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Lošinj, Croatia between 18 and 24 October 2021.

Seeds

 * 1 Rankings are as of 4 October 2021.

Other entrants
The following players received wildcards into the singles main draw:
 * 🇷🇴 Victor Vlad Cornea
 * 🇧🇬 Anthony Genov
 * Mili Poljičak

The following players received entry into the singles main draw as alternates:
 * 🇮🇹 Raúl Brancaccio
 * 🇪🇸 Álvaro López San Martín
 * 🇧🇦 Aldin Šetkić

The following players received entry from the qualifying draw:
 * 🇪🇸 Nicolás Álvarez Varona
 * 🇮🇳 Arjun Kadhe
 * 🇺🇦 Georgii Kravchenko
 * 🇦🇹 Filip Misolic

Singles

 * 🇪🇸 Carlos Taberner def. 🇮🇹 Marco Cecchinato Walkover.

Doubles

 * 🇸🇰 Andrej Martin / 🇦🇹 Tristan-Samuel Weissborn def. 🇷🇴 Victor Vlad Cornea / 🇹🇷 Ergi Kırkın 6–1, 7–6(7–5).