# 1991 Athens Open – Singles

Mark Koevermans was the defending champion, but lost in the quarterfinals this year.
Sergi Bruguera won the tournament, beating Jordi Arrese in the final, 7–5, 6–3.

## Seeds

* Sergi Bruguera (champion)
* Goran Prpić (first round)
* Javier Sánchez (second round)
* Thomas Muster (semifinals)
* Francisco Clavet (semifinals)
* Guillermo Pérez Roldán (quarterfinals)
* Martín Jaite (first round)
* Jordi Arrese (final)

## 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 |
| 1 | Sergi Bruguera | 1 | 6 | 6 | | | | |
| 4 | Thomas Muster | 6 | 2 | 0 | | | | |
| 4 | Thomas Muster | 6 | 2 | 0 | 1 | Sergi Bruguera | 7 | 6 |
| | | | | | 8 | Jordi Arrese | 5 | 3 |
| 5 | Francisco Clavet | 5 | 2 | | 8 | Jordi Arrese | 5 | 3 |
| 8 | Jordi Arrese | 7 | 6 | | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | S Bruguera | 6 | 7 | | | | | | | | | | | | | | | |
| | P Kühnen | 2 | 5 | | 1 | S Bruguera | 6 | 6 | | | | | | | | | | |
| Q | M Velev | 4 | 3 | | Q | W Kowalski | 2 | 1 | | | | | | | | | | |
| Q | W Kowalski | 6 | 6 | | | | | | 1 | S Bruguera | 6 | 6 | | | | | | |
| | M Vajda | 3 | 2 | | | | | | | R Furlan | 2 | 2 | | | | | | |
| | J Wöhrmann | 6 | 6 | | | J Wöhrmann | 5 | 0 | | | | | | | | | | |
| | R Furlan | 6 | 3 | 6 | | R Furlan | 7 | 6 | | | | | | | | | | |
| 7 | M Jaite | 1 | 6 | 3 | | | | | | | | | | 1 | S Bruguera | 1 | 6 | 6 |
| 4 | T Muster | 6 | 6 | | | | | | | | | | | 4 | T Muster | 6 | 2 | 0 |
| | J Eltingh | 4 | 3 | | 4 | T Muster | 6 | 6 | | | | | | | | | | |
| | F Yunis | 6 | 3 | 7$^7$ | | F Yunis | 4 | 3 | | | | | | | | | | |
| | JC Báguena | 2 | 6 | 6$^5$ | | | | | 4 | T Muster | 6 | 3 | 7$^7$ | | | | | |
| WC | G Kalovelonis | 4 | 6 | 3 | | | | | 6 | G Pérez Roldán | 3 | 6 | 6$^3$ | | | | | |
| | B Wuyts | 6 | 3 | 6 | | B Wuyts | 1 | 2 | | | | | | | | | | |
| WC | A Bavelas | 3 | 1 | | 6 | G Pérez Roldán | 6 | 6 | | | | | | | | | | |
| 6 | G Pérez Roldán | 6 | 6 | | | | | | | | | | | | | | | |

### 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 |
| 5 | F Clavet | 7$^7$ | 6 | | | | | | | | | | | | | | | |
| | E Masso | 6$^5$ | 3 | | 5 | F Clavet | 4 | 6 | 6 | | | | | | | | | |
| | R Azar | 6 | 6 | | | R Azar | 6 | 4 | 0 | | | | | | | | | |
| Q | A Gaudenzi | 3 | 0 | | | | | | | 5 | F Clavet | 7$^7$ | 6 | | | | | |
| | L Jonsson | 6 | 0 | 6 | | | | | | | L Jonsson | 6$^5$ | 1 | | | | | |
| | M Filippini | 2 | 6 | 3 | | L Jonsson | 6 | 3 | 6 | | | | | | | | | |
| | B Karbacher | 4 | 6$^3$ | | 3 | J Sánchez | 4 | 6 | 4 | | | | | | | | | |
| 3 | J Sánchez | 6 | 7$^7$ | | | | | | | | | | | | 5 | F Clavet | 5 | 2 |
| 8 | J Arrese | 7$^8$ | 6 | | | | | | | | | | | | 8 | J Arrese | 7 | 6 |
| Q | T Theine | 6$^6$ | 1 | | 8 | J Arrese | 6 | 6 | | | | | | | | | | |
| | C Pistolesi | 2 | 6 | 1 | | G Markus | 2 | 4 | | | | | | | | | | |
| | G Markus | 6 | 3 | 6 | | | | | | 8 | J Arrese | 2 | 6 | 6 | | | | |
| | TJ Middleton | 1 | 2 | | | | | | | | M Koevermans | 6 | 3 | 4 | | | | |
| | M Koevermans | 6 | 6 | | | M Koevermans | 6 | 6 | | | | | | | | | | |
| | M Zoecke | 7$^7$ | 3 | 6 | | M Zoecke | 0 | 2 | | | | | | | | | | |
| 2 | G Prpić | 6$^4$ | 6 | 4 | | | | | | | | | | | | | | |