# 2025 Oeiras Indoors III – Singles

Aleksandar Kovacevic was the defending champion but chose not to defend his title.
Alexander Blockx won the title after defeating Liam Draxl 7–5, 6–1 in the final.

## Seeds

* Márton Fucsovics (second round)
* Christopher Eubanks (first round)
* Jesper de Jong (first round)
* Alexander Ritschard (first round)
* Raphaël Collignon (first round)
* Dominik Koepfer (first round)
* Jaime Faria (first round)
* Lukáš Klein (first round)

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking

### Finals

| Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| | Alexis Galarneau | 4 | 6 | 2 | | | | |
| Q | Liam Draxl | 6 | 4 | 6 | | | | |
| Q | Liam Draxl | 6 | 4 | 6 | Q | Liam Draxl | 5 | 1 |
| | | | | | | Alexander Blockx | 7 | 6 |
| | Alexander Blockx | 7 | 7 | | | Alexander Blockx | 7 | 6 |
| Q | Mark Lajal | 5 | 5 | | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | M Fucsovics | 6 | 6$^3$ | 6 | | | | | | | | | | | | | | |
| | A Moro Cañas | 4 | 7$^7$ | 3 | 1 | M Fucsovics | 3 | 4 | | | | | | | | | | |
| WC | F Ferreira Silva | 3 | 6 | 5 | | A Galarneau | 6 | 6 | | | | | | | | | | |
| | A Galarneau | 6 | 2 | 7 | | | | | | | A Galarneau | 6 | 7$^8$ | | | | | |
| | V Royer | 6 | 6 | | | | | | | | V Royer | 4 | 6$^6$ | | | | | |
| Q | I Buse | 0 | 2 | | | V Royer | 6 | 2 | 6 | | | | | | | | | |
| Q | D Yevseyev | 6 | 6 | | Q | D Yevseyev | 2 | 6 | 4 | | | | | | | | | |
| 8 | L Klein | 4 | 0 | | | | | | | | | | | | A Galarneau | 4 | 6 | 2 |
| 3 | J de Jong | 4 | 5 | | | | | | | | | | | Q | L Draxl | 6 | 4 | 6 |
| Q | L Draxl | 6 | 7 | | Q | L Draxl | 6 | 6 | | | | | | | | | | |
| WC | Pedro Araújo | 7$^9$ | 6 | | WC | P Araújo | 1 | 2 | | | | | | | | | | |
| | J Choinski | 6$^7$ | 4 | | | | | | | Q | L Draxl | 7$^7$ | 7 | | | | | |
| | C Chidekh | 4 | 6 | 6$^5$ | | | | | | Alt | N Mejía | 6$^3$ | 5 | | | | | |
| Alt | A Andreev | 6 | 4 | 7$^7$ | Alt | A Andreev | | | | | | | | | | | | |
| Alt | N Mejía | 6$^3$ | 7$^7$ | 6 | Alt | N Mejía | w/o | | | | | | | | | | | |
| 6 | D Koepfer | 7$^7$ | 6$^5$ | 3 | | | | | | | | | | | | | | |

### Bottom half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 7 | J Faria | 3 | 2 | | | | | | | | | | | | | | | |
| | M-A Hüsler | 6 | 6 | | | M-A Hüsler | 6 | 2 | 2 | | | | | | | | | |
| Alt | N Basilashvili | 6 | 6 | | Alt | N Basilashvili | 4 | 6 | 6 | | | | | | | | | |
| | R Albot | 3 | 4 | | | | | | | Alt | N Basilashvili | 3 | 4 | | | | | |
| Q | D Rincón | 1 | 6 | 0 | | | | | | | A Blockx | 6 | 6 | | | | | |
| | J Rodionov | 6 | 1 | 6 | | J Rodionov | 0 | 6 | 3 | | | | | | | | | |
| | A Blockx | 7$^7$ | 3 | 6 | | A Blockx | 6 | 2 | 6 | | | | | | | | | |
| 4 | A Ritschard | 6$^3$ | 6 | 2 | | | | | | | | | | | | A Blockx | 7 | 7 |
| 5 | R Collignon | 3 | 2 | | | | | | | | | | | | Q | M Lajal | 5 | 5 |
| | D Popko | 6 | 6 | | | D Popko | 3 | 6$^3$ | | | | | | | | | | |
| Q | B Zhukayev | 6 | 6 | | Q | B Zhukayev | 6 | 7$^7$ | | | | | | | | | | |
| WC | G Elias | 3 | 2 | | | | | | | Q | B Zhukayev | 7 | 6$^5$ | 4 | | | | |
| | H Rocha | 6 | 2 | 6$^5$ | | | | | | Q | M Lajal | 5 | 7$^7$ | 6 | | | | |
| Q | M Lajal | 3 | 6 | 7$^7$ | Q | M Lajal | 6 | 6 | | | | | | | | | | |
| | Y Uchiyama | 7$^8$ | 6 | | | Y Uchiyama | 3 | 2 | | | | | | | | | | |
| 2 | C Eubanks | 6$^6$ | 4 | | | | | | | | | | | | | | | |