2023 Open de Oeiras II

The 2023 Open de Oeiras II was a professional tennis tournament played on clay courts. It was the ninth edition of the tournament which was part of the 2023 ATP Challenger Tour. It took place in Oeiras, Portugal between 15 and 20 May 2023.

Seeds

 * 1 Rankings are as of 8 May 2023.

Other entrants
The following players received wildcards into the singles main draw:
 * João Domingues
 * Frederico Ferreira Silva
 * Pedro Sousa

The following players received entry into the singles main draw as alternates:
 * 🇧🇬 Adrian Andreev
 * 🇦🇷 Federico Delbonis

The following players received entry from the qualifying draw:
 * 🇺🇸 Ulises Blanch
 * 🇮🇹 Alessandro Giannessi
 * 🇫🇷 Manuel Guinard
 * 🇧🇷 Eduardo Ribeiro
 * Nino Serdarušić
 * 🇭🇺 Máté Valkusz

Singles

 * 🇦🇷 Facundo Díaz Acosta def. 🇦🇺 Aleksandar Vukic 6–4, 6–3.

Doubles

 * 🇬🇧 Luke Johnson / Sem Verbeek def.  Jaime Faria /  Henrique Rocha 6–7(6–8), 7–5, [10–6].