2023 Estoril Open

The 2023 Estoril Open (also known as the Millennium Estoril Open for sponsorship reasons) was a men's tennis tournament played on outdoor clay courts. It was the 8th edition of the tournament and part of the ATP Tour 250 series of the 2023 ATP Tour. It took place at the Clube de Ténis do Estoril in Cascais, Portugal, from 3 to 9 April 2023.

Singles

 * 🇳🇴 Casper Ruud def. 🇷🇸 Miomir Kecmanović, 6–2, 7–6(7–3)

Doubles

 * 🇧🇪 Sander Gillé / 🇧🇪 Joran Vliegen def. 🇷🇸Nikola Ćaćić / 🇷🇸 Miomir Kecmanović, 6–3, 6–4

Prize money

 * per team

Seeds

 * 1 Rankings are as of 20 March 2023

Other entrants
The following players received wildcards into the main draw:
 * 🇪🇸 Roberto Bautista Agut
 * 🇺🇸 Ben Shelton
 * João Sousa

The following players received entry as an emergency substitution:
 * 🇵🇱 Hubert Hurkacz

The following players received entry from the qualifying draw:
 * 🇮🇹 Alessandro Giannessi
 * 🇦🇹 Sebastian Ofner
 * Henrique Rocha
 * Pedro Sousa

Withdrawals

 * 🇫🇷 Grégoire Barrère → replaced by Tseng Chun-hsin
 * 🇪🇸 Pablo Carreño Busta → replaced by 🇦🇹 Dominic Thiem
 * 🇺🇸 Sebastian Korda → replaced by 🇵🇱 Hubert Hurkacz
 * 🇷🇸 Dušan Lajović → replaced by 🇦🇹 Jurij Rodionov
 * 🇫🇮 Emil Ruusuvuori → replaced by 🇫🇷 Luca Van Assche
 * 🇸🇪 Mikael Ymer → replaced by 🇲🇩 Radu Albot

Seeds

 * Rankings are as of 20 March 2023

Other entrants
The following pairs received wildcards into the doubles main draw:
 * 🇺🇸 Ben Shelton / Duarte Vale
 * João Sousa / 🇦🇹 Dominic Thiem

Withdrawals

 * Marcelo Arévalo / Jean-Julien Rojer → replaced by 🇪🇨 Diego Hidalgo / 🇨🇴 Cristian Rodríguez
 * 🇧🇦 Tomislav Brkić / 🇪🇨 Gonzalo Escobar → replaced by 🇪🇨 Gonzalo Escobar / 🇫🇷 Fabien Reboul
 * 🇬🇧 Lloyd Glasspool / 🇫🇮 Harri Heliövaara → replaced by 🇦🇺 Andrew Harris / 🇦🇺 John-Patrick Smith
 * 🇩🇪 Kevin Krawietz / 🇩🇪 Tim Pütz → replaced by 🇮🇹 Marco Cecchinato / 🇫🇷 Quentin Halys
 * 🇧🇷 Rafael Matos / 🇪🇸 David Vega Hernández → replaced by Romain Arneodo / 🇦🇹 Sam Weissborn
 * 🇬🇧 Jamie Murray / 🇳🇿 Michael Venus → replaced by 🇲🇩 Radu Albot / 🇷🇴 Victor Vlad Cornea
 * Hugo Nys / 🇵🇱 Jan Zieliński → replaced by 🇩🇪 Andreas Mies / Hugo Nys