The 2018 Estoril Open (also known as the Millennium Estoril Open for sponsorship purposes) was a professional men's tennis tournament played on outdoor clay courts. It was the fourth edition of the Estoril Open, and part of the ATP World Tour 250 series of the 2018 ATP World Tour. The event took place at the Clube de Ténis do Estoril in Cascais, Portugal, from April 30 through May 6, 2018.
| 2018 Estoril Open | |
|---|---|
| Date | 30 April – 6 May |
| Edition | 4th |
| Draw | 28S / 16D |
| Prize money | €501,345 |
| Surface | Clay |
| Location | Cascais, Portugal |
| Venue | Clube de Ténis do Estoril |
| Champions | |
| Singles | |
 João Sousa | |
| Doubles | |
 Kyle Edmund / Cameron Norrie | |
Singles main-draw entrants edit
Seeds edit
| Country | Player | Rank1 | Seed |
|---|---|---|---|
 RSA
|
Kevin Anderson | 8 | 1 |
 ESP
|
Pablo Carreño Busta | 11 | 2 |
| GBR
|
Kyle Edmund | 23 | 3 |
 LUX
|
Gilles Müller | 28 | 4 |
| ESP
|
Albert Ramos Viñolas | 40 | 5 |
 NED
|
Robin Haase | 44 | 6 |
 ARG
|
Leonardo Mayer | 45 | 7 |
 RUS
|
Daniil Medvedev | 48 | 8 |
- Rankings are as of April 23, 2018.
Other entrants edit
The following players received wildcards into the singles main draw:
The following players received entry from the qualifying draw:
Withdrawals edit
- Before the tournament
David Ferrer → replaced by 
Cameron Norrie
Nick Kyrgios → replaced by 
Nicolás Kicker
Benoît Paire → replaced by 
Gastão Elias
Doubles main-draw entrants edit
Seeds edit
| Country | Player | Country | Player | Rank1 | Seed |
|---|---|---|---|---|---|
 AUS
|
John Peers | NED
|
Jean-Julien Rojer | 17 | 1 |
| RSA
|
Raven Klaasen |  NZL
|
Michael Venus | 48 | 2 |
| ESP
|
Marc López | ESP
|
David Marrero | 67 | 3 |
 BRA
|
Marcelo Demoliner |  MEX
|
Santiago González | 84 | 4 |
- Rankings are as of April 23, 2018.
Other entrants edit
The following pairs received wildcards into the doubles main draw:
Champions edit
Singles edit
- João Sousa def.
Frances Tiafoe, 6–4, 6–4
Doubles edit
- Kyle Edmund / Cameron Norrie def.
Wesley Koolhof / 
Artem Sitak, 6–4, 6–2