| 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.
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.
Thomas Muster was the defending champion of the singles event at the Australian Men's Hardcourt Championships tennis tournament, but did not participate this year.
MaliVai Washington was the defending champion, but lost in the first round this year.
Andrei Chesnokov was the defending champion, but did not participate this year.
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Paul Annacone was the defending champion but lost in the second round to Thomas Muster.
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Andrei Cherkasov was the defending champion and won in the final 7–6(7–2), 3–6, 7–6(7–5), against Jakob Hlasek.
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Karel Nováček was the defending champion, but lost in the first round this year.
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Marc Rosset was the defending champion, but lost in the semifinals this year.
Andrei Chesnokov was the defending champion, but lost in the second round to Fabrice Santoro.
Emilio Sánchez was the defending champion, but lost in the second round to Francisco Roig.
Thomas Muster was the defending champion, but did not compete this year.
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Thomas Muster was the defending champion, but did not compete this year.