# 1991 Mercedes Cup – Singles

Goran Ivanišević was the defending champion, but lost in the second round to Andrés Gómez.
Michael Stich won the title by defeating Alberto Mancini 1–6, 7–6$^{(11–9)}$, 6–4, 6–2 in the final.

## Seeds

All seeds received a bye to the second round.
* Michael Stich (champion)
* Guy Forget (third round)
* Emilio Sánchez (second round)
* Goran Ivanišević (second round)
* Andrei Cherkasov (second round)
* Karel Nováček (second round)
* Goran Prpić (quarterfinals)
* Magnus Gustafsson (second round)
* Horst Skoff (third round)
* Jonas Svensson (second round)
* Guillermo Pérez Roldán (third round)
* Alexander Volkov (third round)
* Omar Camporese (second round)
* Ronald Agénor (third round)
* Martín Jaite (second round)
* Jordi Arrese (second round)

## 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

| Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final | Final | Final | |
| 1 | Michael Stich | 6 | 3 | 7$^7$ | | | | | | | | | | | | |
| | Richard Krajicek | 4 | 6 | 6$^2$ | | | | | | | | | | | | |
| | Richard Krajicek | 4 | 6 | 6$^2$ | 1 | Michael Stich | 6 | 6 | | | | | | | | |
| | | | | | | Francisco Clavet | 4 | 2 | | | | | | | | |
| | Francisco Clavet | 6 | 6$^3$ | 6 | | Francisco Clavet | 4 | 2 | | | | | | | | |
| Q | Cédric Pioline | 3 | 7$^7$ | 1 | | | | | | | | | | | | |
| Q | Cédric Pioline | 3 | 7$^7$ | 1 | | | | | | 1 | Michael Stich | 1 | 7$^{11}$ | 6 | 6 | |
| | | | | | | | | | | | Alberto Mancini | 6 | 6$^9$ | 4 | 2 | |
| | Alberto Mancini | 6 | 6 | | | | | | | | | | | | | Alberto Mancini | 6 | 6$^9$ | 4 | 2 |
| Q | Germán López | 3 | 3 | | | | | | | | | | | | | |
| Q | Germán López | 3 | 3 | | | Alberto Mancini | 4 | 6 | 6 | | | | | | | |
| | | | | | Q | Lars Koslowski | 6 | 1 | 3 | | | | | | | |
| 7 | Goran Prpić | 2 | 6 | 5 | Q | Lars Koslowski | 6 | 1 | 3 | | | | | | | |
| Q | Lars Koslowski | 6 | 2 | 7 | | | | | | | | | | | | |

### Top half
#### Section 1

| First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | 1 | M Stich | 6 | 7$^7$ | | | | | | | | | | |
| WC | U Riglewski | 0 | 1 | | F Santoro | 3 | 6$^3$ | | | | | | | | | | |
| | F Santoro | 6 | 6 | | | | | | 1 | M Stich | 6 | 6 | | | | | |
| | M Larsson | 3 | 0 | | | | | | | J Sánchez | 3 | 3 | | | | | |
| | J Sánchez | 6 | 6 | | J Sánchez | 4 | 6 | 6 | | | | | | | | | |
| | | | | 16 | J Arrese | 6 | 1 | 4 | | | | | | | | | |
| | | | | | | | | | | | | | 1 | M Stich | 6 | 3 | 7$^7$ |
| | | | | | | | | | | | | | | R Krajicek | 4 | 6 | 6$^2$ |
| | | | | 9 | H Skoff | 6 | 6 | | | | | | | | | | |
| | K Curren | 4 | 4 | | H de la Peña | 0 | 3 | | | | | | | | | | |
| | H de la Peña | 6 | 6 | | | | | | 9 | H Skoff | 3 | 4 | | | | | |
| | F Davín | 2 | 4 | | | | | | | R Krajicek | 6 | 6 | | | | | |
| | R Krajicek | 6 | 6 | | R Krajicek | 7$^7$ | 5 | 7$^7$ | | | | | | | | | |
| | | | | 8 | M Gustafsson | 6$^2$ | 7 | 6$^0$ | | | | | | | | | |

#### Section 2

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 4 | G Ivanišević | 6 | 3 | 6$^3$ | | | | | | | | | | |
| | R Furlan | 6 | 2 | 1 | | A Gómez | 4 | 6 | 7$^7$ | | | | | | | | | | |
| | A Gómez | 4 | 6 | 6 | | | | | | | A Gómez | 3 | 3 | | | | | | |
| | T Muster | 1 | 3 | | | | | | | | F Clavet | 6 | 6 | | | | | | |
| | F Clavet | 6 | 6 | | | F Clavet | 7 | 6 | | | | | | | | | | | |
| | | | | | 13 | O Camporese | 5 | 0 | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | F Clavet | 6 | 6$^3$ | 6 |
| | | | | | | | | | | | | | | | Q | C Pioline | 3 | 7$^7$ | 1 |
| | | | | | 12 | A Volkov | 6 | 6 | | | | | | | | | | | |
| Q | J Wöhrmann | 7$^7$ | 4 | 6 | Q | J Wöhrmann | 2 | 3 | | | | | | | | | | | |
| | J Siemerink | 6$^4$ | 6 | 3 | | | | | | 12 | A Volkov | 2 | 6 | 3 | | | | | |
| Q | C Pioline | 6 | 6 | | | | | | | Q | C Pioline | 6 | 4 | 6 | | | | | |
| WC | Y Noah | 3 | 2 | | Q | C Pioline | 6 | 1 | 6 | | | | | | | | | | |
| | | | | | 6 | K Nováček | 1 | 6 | 3 | | | | | | | | | | |

### Bottom half
#### Section 3

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 5 | A Cherkasov | 6 | 4 | 2 | | | | | | | | |
| | A Mancini | 6 | 6 | | | A Mancini | 4 | 6 | 6 | | | | | | | | |
| | P Haarhuis | 4 | 2 | | | | | | | | A Mancini | 7 | 6 | | | | |
| | M Koevermans | 3 | 7$^7$ | 0 | | | | | | 11 | G Pérez Roldán | 5 | 2 | | | | |
| Q | C Costa | 6 | 6$^1$ | 6 | Q | C Costa | 3 | 2 | | | | | | | | | |
| | | | | | 11 | G Pérez Roldán | 6 | 6 | | | | | | | | | |
| | | | | | | | | | | | | | | | A Mancini | 6 | 6 |
| | | | | | | | | | | | | | | Q | G López | 3 | 3 |
| | | | | | 14 | R Agénor | 6 | 3 | 6 | | | | | | | | |
| Q | M Naewie | 2 | 4 | | | M Rosset | 1 | 6 | 3 | | | | | | | | |
| | M Rosset | 6 | 6 | | | | | | | 14 | R Agénor | 2 | 3 | | | | |
| Q | G López | 6$^5$ | 6 | 6 | | | | | | Q | G López | 6 | 6 | | | | |
| WC | T Champion | 7$^7$ | 3 | 2 | Q | G López | 7$^7$ | 7$^{13}$ | | | | | | | | | |
| | | | | | 3 | E Sánchez | 6$^4$ | 6$^{11}$ | | | | | | | | | |

#### Section 4

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 7 | G Prpić | 7$^7$ | 6 | | | | | | | | | | | |
| | M Filippini | 6 | 4 | 7 | | M Filippini | 6$^3$ | 2 | | | | | | | | | | | |
| | N Kulti | 2 | 6 | 5 | | | | | | 7 | G Prpić | 6 | 2 | 6 | | | | | |
| | E Jelen | 0 | 6 | 6 | | | | | | | E Jelen | 3 | 6 | 2 | | | | | |
| WC | CU Steeb | 6 | 3 | 2 | | E Jelen | 7$^7$ | 6 | | | | | | | | | | | |
| | | | | | 10 | J Svensson | 6$^3$ | 1 | | | | | | | | | | | |
| | | | | | | | | | | | | | | | 7 | G Prpić | 2 | 6 | 5 |
| | | | | | | | | | | | | | | | Q | L Koslowski | 6 | 2 | 7 |
| | | | | | 15 | M Jaite | 3 | 4 | | | | | | | | | | | |
| LL | F Roig | 6$^0$ | 6$^2$ | | Q | L Koslowski | 6 | 6 | | | | | | | | | | | |
| Q | L Koslowski | 7$^7$ | 7$^7$ | | | | | | | Q | L Koslowski | 7$^7$ | 7$^{11}$ | | | | | | |
| | M Vajda | 6 | 3 | 3 | | | | | | 2 | G Forget | 6$^5$ | 6$^9$ | | | | | | |
| | W Masur | 4 | 6 | 6 | | W Masur | 7 | 6$^3$ | 6$^7$ | | | | | | | | | | |
| | | | | | 2 | G Forget | 5 | 7$^7$ | 7$^9$ | | | | | | | | | | |