# 2025 San Diego Open – Singles

This was the first edition of the tournament as an ATP Challenger Tour event.
Eliot Spizzirri won the title after defeating Mackenzie McDonald 6–4, 2–6, 6–4 in the final.

## Seeds

* Arthur Cazaux (quarterfinals)
* Tristan Boyer (first round)
* Dominik Koepfer (withdrew)
* Mackenzie McDonald (final)
* Kamil Majchrzak (semifinals)
* Taro Daniel (quarterfinals)
* Mitchell Krueger (second round)
* Ethan Quinn (semifinals)

## 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 | Final |
| 8 | Ethan Quinn | 3 | 6 | 3 | | | | | |
| | Eliot Spizzirri | 6 | 4 | 6 | | | | | |
| | Eliot Spizzirri | 6 | 4 | 6 | | Eliot Spizzirri | 6 | 2 | 6 |
| | | | | | 4 | Mackenzie McDonald | 4 | 6 | 4 |
| 4 | Mackenzie McDonald | 3 | 6 | 6 | 4 | Mackenzie McDonald | 4 | 6 | 4 |
| 5 | Kamil Majchrzak | 6 | 1 | 1 | | | | | |

### 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 | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | A Cazaux | 6 | 6 | | | | | | | | | | | | | | | | |
| | L Tu | 3 | 4 | | 1 | A Cazaux | 7 | 6 | | | | | | | | | | | |
| | C Lestienne | 6 | 6 | | | C Lestienne | 5 | 4 | | | | | | | | | | | |
| LL | Stefan Dostanic | 3 | 4 | | | | | | | 1 | A Cazaux | 5 | 7$^7$ | 4 | | | | | |
| WC | J Brooksby | 6 | 6 | | | | | | | 8 | E Quinn | 7 | 6$^1$ | 6 | | | | | |
| | C Wong | 2 | 4 | | WC | J Brooksby | 3 | 7 | 6$^5$ | | | | | | | | | | |
| Q | A Perez | 4 | 6$^3$ | | 8 | E Quinn | 6 | 5 | 7$^7$ | | | | | | | | | | |
| 8 | E Quinn | 6 | 7$^7$ | | | | | | | | | | | | 8 | E Quinn | 3 | 6 | 3 |
| Q | A Martin | 6 | 3 | 6 | | | | | | | | | | | | E Spizzirri | 6 | 4 | 6 |
| | Z Svajda | 4 | 6 | 3 | Q | A Martin | 6 | 1 | 4 | | | | | | | | | | |
| Q | A Hernández | 3 | 1 | | | E Spizzirri | 1 | 6 | 6 | | | | | | | | | | |
| | E Spizzirri | 6 | 6 | | | | | | | | E Spizzirri | 6$^2$ | 6 | 6 | | | | | |
| Q | A Rybakov | 7$^7$ | 6 | | | | | | | 6 | T Daniel | 7$^7$ | 0 | 4 | | | | | |
| | R Albot | 6$^2$ | 3 | | Q | A Rybakov | 6$^9$ | 6$^1$ | | | | | | | | | | | |
| | T Zink | 4 | 4 | | 6 | T Daniel | 7$^{11}$ | 7$^7$ | | | | | | | | | | | |
| 6 | T Daniel | 6 | 6 | | | | | | | | | | | | | | | | |

### Bottom half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 7 | M Krueger | 6 | 3 | 6 | | | | | | | | | | | | | |
| | A Andrade | 4 | 6 | 1 | 7 | M Krueger | 3 | 3 | | | | | | | | | |
| | J Pinnington Jones | 3 | 6$^4$ | | WC | T Svajda | 6 | 6 | | | | | | | | | |
| WC | T Svajda | 6 | 7$^7$ | | | | | | WC | T Svajda | 3 | 4 | | | | | |
| | M Gigante | 6 | 6 | | | | | | 4 | M McDonald | 6 | 6 | | | | | |
| Q | Rohan Murali | 2 | 4 | | | M Gigante | 3 | 5 | | | | | | | | | |
| | Karue Sell | 3 | 3 | | 4 | M McDonald | 6 | 7 | | | | | | | | | |
| 4 | M McDonald | 6 | 6 | | | | | | | | | | 4 | M McDonald | 3 | 6 | 6 |
| 5 | K Majchrzak | 7$^7$ | 6 | | | | | | | | | | 5 | K Majchrzak | 6 | 1 | 1 |
| | C Smith | 6$^3$ | 4 | | 5 | K Majchrzak | 7 | 7 | | | | | | | | | |
| Q | B Bicknell | 6 | 6$^4$ | 4 | | M Mmoh | 5 | 5 | | | | | | | | | |
| | M Mmoh | 2 | 7$^7$ | 6 | | | | | 5 | K Majchrzak | 7$^7$ | 1 | | | | | |
| | T Atmane | 6$^5$ | 6 | 5 | | | | | | A Bolt | 6$^2$ | 1$^r$ | | | | | |
| Alt | G Nanda | 7$^7$ | 4 | 7 | Alt | G Nanda | 4 | 3 | | | | | | | | | |
| | A Bolt | 6 | 7$^7$ | | | A Bolt | 6 | 6 | | | | | | | | | |
| 2/WC | T Boyer | 3 | 6$^4$ | | | | | | | | | | | | | | |