| Singles | |
|---|---|
| 1991 Geneva Open | |
| Champion |  Thomas Muster |
| Runner-up | Horst Skoff |
| Score | 6–2, 6–4 |
| Draw | 32 |
| Seeds | 8 |
Horst Skoff was the defending champion, but lost in the final this year.
Thomas Muster won the title, defeating Skoff 6–2, 6–4 in the final. [1]
Sergi Bruguera (quarterfinals)
Andrei Cherkasov (first round)
Goran Prpić (second round) Horst Skoff (final)
Alberto Mancini (second round)
Marc Rosset (first round) Guillermo Pérez Roldán (second round)
Omar Camporese (first round)| Semifinals | Final | ||||||||||||
| Thomas Muster | 77 | 77 | |||||||||||
| WC |  Andrei Medvedev | 63 | 65 | ||||||||||
| Thomas Muster | 6 | 6 | |||||||||||
| 4 | Horst Skoff | 2 | 4 | ||||||||||
| 4 | Horst Skoff | 710 | 6 | ||||||||||
| Jordi Arrese | 68 | 2 | |||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | S Bruguera | 6 | 6 | ||||||||||||||||||||||||
 B Wuyts | 3 | 2 | 1 | S Bruguera | 78 | 1 | 6 | ||||||||||||||||||||
| WC | C Mezzadri | 6 | 7 | WC | C Mezzadri | 66 | 6 | 1 | |||||||||||||||||||
| WC |  T Tulasne | 3 | 5 | 1 | S Bruguera | 6 | 4 | 4 | |||||||||||||||||||
| T Muster | 6 | 7 | T Muster | 4 | 6 | 6 | |||||||||||||||||||||
 M Vajda | 3 | 5 | T Muster | 4 | 6 | 6 | |||||||||||||||||||||
 M Filippini | 61 | 3 | 7 | G Pérez Roldán | 6 | 1 | 2 | ||||||||||||||||||||
| 7 | G Pérez Roldán | 77 | 6 | T Muster | 77 | 77 | |||||||||||||||||||||
| 3 | G Prpić | 4 | 6 | 6 | WC | A Medvedev | 63 | 65 | |||||||||||||||||||
 G Bloom | 6 | 4 | 4 | 3 | G Prpić | 79 | 0 | 5 | |||||||||||||||||||
| R Furlan | 4 | 5 | Q | C Miniussi | 67 | 6 | 7 | ||||||||||||||||||||
| Q | C Miniussi | 6 | 7 | Q | C Miniussi | 4 | 7 | 5 | |||||||||||||||||||
 J Gunnarsson | 3 | 3 | WC | A Medvedev | 6 | 5 | 7 | ||||||||||||||||||||
| E Masso | 6 | 6 | E Masso | 7 | 63 | 1 | |||||||||||||||||||||
| WC | A Medvedev | 6 | 6 | WC | A Medvedev | 5 | 77 | 6 | |||||||||||||||||||
| 6 | M Rosset | 2 | 1 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 5 | A Mancini | 6 | 77 | ||||||||||||||||||||||||
 L Mattar | 3 | 65 | 5 | A Mancini | 1 | 6 | 4 | ||||||||||||||||||||
| H de la Peña | 77 | 77 | H de la Peña | 6 | 3 | 6 | |||||||||||||||||||||
| F Davín | 65 | 64 | H de la Peña | 63 | 6 | 1 | |||||||||||||||||||||
 P Baur | 6 | 65 | 5 | 4 | H Skoff | 77 | 4 | 6 | |||||||||||||||||||
| Q |  M Merz | 3 | 77 | 7 | Q | M Merz | 2 | 0 | |||||||||||||||||||
| G López | 2 | 0 | 4 | H Skoff | 6 | 6 | |||||||||||||||||||||
| 4 | H Skoff | 6 | 6 | 4 | H Skoff | 710 | 6 | ||||||||||||||||||||
| 8 | O Camporese | 3 | 4 | J Arrese | 68 | 2 | |||||||||||||||||||||
| Q | C Arriens | 6 | 6 | Q | C Arriens | 5 | 7 | 5 | |||||||||||||||||||
| J Oncins | 6 | 7 | J Oncins | 7 | 5 | 7 | |||||||||||||||||||||
| Q | J Gisbert-Schultze | 4 | 5 | J Oncins | 6 | 4 | 5 | ||||||||||||||||||||
 V Paloheimo | 77 | 4 | 6 | J Arrese | 4 | 6 | 7 | ||||||||||||||||||||
 R Agénor | 65 | 6 | 4 | V Paloheimo | 2 | 6 | 5 | ||||||||||||||||||||
| J Arrese | 6 | 4 | 6 | J Arrese | 6 | 3 | 7 | ||||||||||||||||||||
| 2 | A Cherkasov | 4 | 6 | 1 | |||||||||||||||||||||||
Goran Ivanišević defeated Pete Sampras 6–4, 6–4 in the final to secure the title.
Nicklas Kulti was the defending champion, but lost in the first round this year.
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