| Singles | |
|---|---|
| 1990 Casablanca Open | |
| Champion |  Thomas Muster |
| Runner-up |  Guillermo Pérez Roldán |
| Score | 6–1, 6–7(3–7), 6–2 |
| Draw | 32 |
| Seeds | 8 |
Tarik Benhabiles was the defending champion but lost in the second round to Thomas Muster.
Muster won in the final, 6–1, 6–7(3–7), 6–2, against Guillermo Pérez Roldán.
Guillermo Pérez Roldán (final) Thomas Muster (champion)
Goran Prpić (semifinals)
Martin Střelba (first round)
Paul Haarhuis (first round)
Tomás Carbonell (semifinals) Mark Koevermans (quarterfinals) Franco Davín (second round)| Semifinals | Final | ||||||||||||
| 1 | Guillermo Pérez Roldán | 6 | 6 | ||||||||||
| 6 | Tomás Carbonell | 1 | 1 | ||||||||||
| 1 | Guillermo Pérez Roldán | 1 | 77 | 2 | |||||||||
| 2 | Thomas Muster | 6 | 63 | 6 | |||||||||
| 3 | Goran Prpić | 1 | 3 | ||||||||||
| 2 | Thomas Muster | 6 | 6 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | G Pérez Roldán | 77 | 6 | ||||||||||||||||||||||||
| Q |  T Woodbridge | 63 | 1 | 1 | G Pérez Roldán | 3 | 6 | 6 | |||||||||||||||||||
| R Fromberg | 6 | 4 | 6 | R Fromberg | 6 | 3 | 3 | ||||||||||||||||||||
| Q |  M Larsson | 2 | 6 | 2 | 1 | G Pérez Roldán | 6 | 7 | |||||||||||||||||||
| N Kulti | 5 | 0 |  T Tulasne | 2 | 5 | ||||||||||||||||||||||
| T Tulasne | 7 | 6 | T Tulasne | 6 | 6 | ||||||||||||||||||||||
| S Youl | 2 | 1 | 8 | F Davín | 3 | 2 | |||||||||||||||||||||
| 8 | F Davín | 6 | 6 | 1 | G Pérez Roldán | 6 | 6 | ||||||||||||||||||||
| 4 | M Střelba | 1 | 0 | 6 | T Carbonell | 1 | 1 | ||||||||||||||||||||
| F Luna | 6 | 6 | F Luna | 3 | 63 | ||||||||||||||||||||||
| L Jönsson | 3 | 5 | R Azar | 6 | 77 | ||||||||||||||||||||||
| R Azar | 6 | 7 | R Azar | 5 | 6 | 3 | |||||||||||||||||||||
 M Wostenholme | 6 | 6 | 6 | T Carbonell | 7 | 2 | 6 | ||||||||||||||||||||
| WC |  K Outaleb | 4 | 4 | M Wostenholme | 1 | 4 | |||||||||||||||||||||
| F Roig | 4 | 2 | 6 | T Carbonell | 6 | 6 | |||||||||||||||||||||
| 6 | T Carbonell | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 5 | P Haarhuis | 6 | 2 | 3 | |||||||||||||||||||||||
| Q | N Utgren | 1 | 6 | 6 | Q | N Utgren | 6 | 4 | 3 | ||||||||||||||||||
| WC | K Alami | 4 | 5 | J Anderson | 0 | 6 | 6 | ||||||||||||||||||||
| J Anderson | 6 | 7 | J Anderson | 3 | 1 | ||||||||||||||||||||||
| Q | T Champion | 6 | 6 | 3 | G Prpić | 6 | 6 | ||||||||||||||||||||
| J Stoltenberg | 3 | 2 | Q | T Champion | 5 | 66 | |||||||||||||||||||||
| WC | Y El Aynaoui | 2 | 67 | 3 | G Prpić | 7 | 78 | ||||||||||||||||||||
| 3 | G Prpić | 6 | 79 | 3 | G Prpić | 1 | 3 | ||||||||||||||||||||
| 7 | M Koevermans | 6 | 6 | 2 | T Muster | 6 | 6 | ||||||||||||||||||||
 S Colombo | 1 | 4 | 7 | M Koevermans | 6 | 1 | 6 | ||||||||||||||||||||
| M Vajda | 6 | 6 | M Vajda | 1 | 6 | 3 | |||||||||||||||||||||
| J F Altur | 3 | 2 | 7 | M Koevermans | 4 | 64 | |||||||||||||||||||||
| T Benhabiles | 6 | 6 | 2 | T Muster | 6 | 77 | |||||||||||||||||||||
 L Lavalle | 0 | 2 | T Benhabiles | 6 | 1 | 2 | |||||||||||||||||||||
 A Võsand | 2 | 5 | 2 | T Muster | 4 | 6 | 6 | ||||||||||||||||||||
| 2 | T Muster | 6 | 7 | ||||||||||||||||||||||||
Emilio Sánchez was the defending champion, but lost in the first round this year.
The 1991 BMW Open Singles was the singles bracket of the 1991 BMW Open. The title was won by Magnus Gustafsson, defeating Guillermo Pérez Roldán. Roldán retired while Gustafsson was leading 3–6, 6–3, 4–3. Karel Nováček, the defending champion from the prior year singles event, did not participate.
Guillermo Pérez Roldán won the title, defeating Germán López 2–6, 7–5, 6–3 in the final.
Andrei Chesnokov defeated Thomas Muster in the final, 7–5, 6–3, 6–3 to win the singles tennis title at the 1990 Monte Carlo Open.
Thomas Muster defeated Andrei Chesnokov in the final, 6–1, 6–3, 6–1 to win the men's singles tennis title at the 1990 Italian Open.
Tim Mayotte was the defending champion but lost in the semifinals to Brad Gilbert.
Mats Wilander was the defending champion but lost in the third round to Alberto Mancini.
Mark Koevermans was the defending champion, but lost in the quarterfinals this year.
Ronald Agénor was the defending champion, but did not participate this year.
Horst Skoff was the defending champion, but lost in the final this year.
Emilio Sánchez won the men's singles tennis title at the 1991 Italian Open after Alberto Mancini retired from the final, with the scoreline at 6–3, 6–1, 3–0.
Guillermo Pérez Roldán was the defending champion, but lost in the semifinals to tournament runner-up Juan Aguilera.
Mats Wilander was the defending champion, but did not compete this year.
The 1991 PCzechoslovak Open was a men's tennis tournament played on Clay in Prague, Czech Republic that was part of the International Series of the 1991 ATP Tour. Jordi Arrese was the defending champion, but lost in the second round to Thomas Muster.
Dimitri Poliakov was the defending champion, but did not compete this year.
Thomas Muster was the defending champion, but lost in the quarterfinals to Guillermo Pérez Roldán.
Martín Jaite was the defending champion, but lost in the second round to Karel Nováček.
Ivan Lendl was the defending champion, but did not compete this year.
Marcelo Filippini was the defending champion, but lost in the second round to Nicklas Kulti.
Thomas Muster successfully defended his title by defeating Alberto Berasategui 7–5, 3–6, 6–3 in the final.