| 2025 Estoril Open | |
|---|---|
| Date | 29 April – 4 May |
| Edition | 10th |
| Category | ATP Challenger Tour |
| Draw | 28S / 16D |
| Surface | Clay / outdoor |
| Location | Cascais, Portugal |
| Venue | Clube de Ténis do Estoril |
| Champions | |
| Singles | |
 Alex Michelsen | |
| Doubles | |
 Ariel Behar /  Joran Vliegen | |
The 2025 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 10th edition of the tournament and an ATP Challenger Tour 175 event on the 2025 ATP Challenger Tour (downgraded from ATP 250 status in previous years). It took place at the Clube de Ténis do Estoril in Cascais, Portugal, from 29 April to 4 May 2025.[1]
| Country | Player | Rank1 | Seed |
|---|---|---|---|
 CAN
|
Félix Auger-Aliassime | 19 | 1 |
| USA
|
Alex Michelsen | 38 | 2 |
 POR
|
Nuno Borges | 41 | 3 |
| USA
|
Marcos Giron | 45 | 4 |
 SRB
|
Miomir Kecmanović | 47 | 5 |
 ESP
|
Pedro Martínez | 48 | 6 |
 CHI
|
Nicolás Jarry | 57 | 7 |
 BRA
|
João Fonseca | 65 | 8 |
The following players received wildcards into the main draw:
The following players received entry into the singles main draw as alternates:
The following players received entry from the qualifying draw:
The following players received entry as lucky losers:
Alex Michelsen def. 
Andrea Pellegrino 6–4, 6–4. Ariel Behar / Joran Vliegen def. Francisco Cabral / 
Lucas Miedler 7–5, 6–3.
