2021 Open de Oeiras II

The 2021 Open de Oeiras II was a professional tennis tournament played on clay courts. It was the second edition of the tournament, part of the 2021 ATP Challenger Tour. It took place in Oeiras, Portugal between 5 and 11 April 2021.

Seeds

 * 1 Rankings are as of 22 March 2021.

Other entrants
The following players received wildcards into the singles main draw:
 * Pedro Araújo
 * Nuno Borges
 * Tiago Cação

The following player received entry into the singles main draw as a special exempt:
 * Gastão Elias

The following players received entry into the singles main draw as alternates:
 * 🇦🇺 Harry Bourchier
 * 🇨🇿 Jonáš Forejtek

The following players received entry from the qualifying draw:
 * 🇧🇬 Adrian Andreev
 * 🇮🇹 Raúl Brancaccio
 * 🇦🇷 Pedro Cachin
 * 🇫🇷 Evan Furness

Singles

 * 🇦🇷 Pedro Cachin def. Nuno Borges 7–6(7–4), 7–6(7–3).

Doubles

 * Nuno Borges / Francisco Cabral def. 🇷🇺 Pavel Kotov /  Tseng Chun-hsin 6–1, 6–2.