# 1991 Swiss Indoors – Singles

John McEnroe was the defending champion, but lost in the final to Jakob Hlasek. The score was 7–6$^{(7–4)}$, 6–0, 6–3.

## Seeds

* Michael Stich (first round)
* Karel Nováček (quarterfinals)
* Sergi Bruguera (second round)
* Petr Korda (second round)
* Andrei Cherkasov (first round)
* Jakob Hlasek (champion)
* Alexander Volkov (semifinals)
* John McEnroe (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 | Final |
| 8 | John McEnroe | 6 | 6 | | | | | | |
| WC | Jimmy Connors | 1 | 3 | | | | | | |
| WC | Jimmy Connors | 1 | 3 | | 8 | John McEnroe | 6$^4$ | 0 | 3 |
| | | | | | 6 | Jakob Hlasek | 7$^7$ | 6 | 6 |
| 6 | Jakob Hlasek | 7$^7$ | 6$^5$ | 7$^7$ | 6 | Jakob Hlasek | 7$^7$ | 6 | 6 |
| 7 | Alexander Volkov | 6$^3$ | 7$^7$ | 6$^5$ | | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | M Stich | 3 | 3 | | | | | | | | | | | | | |
| | C Bergström | 6 | 6 | | | C Bergström | 6 | 6 | | | | | | | | |
| Q | J Carlsson | 7 | 5 | 6 | Q | J Carlsson | 3 | 2 | | | | | | | | |
| | A Mronz | 5 | 7 | 3 | | | | | | C Bergström | 6$^3$ | 4 | | | | |
| | P McEnroe | 6$^3$ | 7 | 6 | | | | | 8 | J McEnroe | 7$^7$ | 6 | | | | |
| WC | C Mezzadri | 7$^7$ | 5 | 0 | | P McEnroe | 2 | 4 | | | | | | | | |
| Q | T Guardiola | 2 | 4 | | 8 | J McEnroe | 6 | 6 | | | | | | | | |
| 8 | J McEnroe | 6 | 6 | | | | | | | | | | 8 | J McEnroe | 6 | 6 |
| 4 | P Korda | 3 | 6 | 6 | | | | | | | | | WC | J Connors | 1 | 3 |
| | A Järryd | 6 | 4 | 3 | 4 | P Korda | 3 | 4 | | | | | | | | |
| Q | L Prades | 3 | 1 | | WC | J Connors | 6 | 6 | | | | | | | | |
| WC | J Connors | 6 | 6 | | | | | | WC | J Connors | 6 | 6 | | | | |
| | P Canè | 4 | 6 | 7$^7$ | | | | | | A Mansdorf | 3 | 2 | | | | |
| WC | T Enqvist | 6 | 3 | 6$^5$ | | P Canè | 5 | 4 | | | | | | | | |
| | A Mansdorf | 1 | 6 | 6 | | A Mansdorf | 7 | 6 | | | | | | | | |
| 5 | A Cherkasov | 6 | 3 | 3 | | | | | | | | | | | | |

### 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 | Semifinals |
| 6 | J Hlasek | 6 | 6 | | | | | | | | | | | | | | | | |
| | J Gunnarsson | 3 | 2 | | 6 | J Hlasek | 7$^{10}$ | 6 | | | | | | | | | | | |
| | CU Steeb | 6 | 7$^7$ | | | CU Steeb | 6$^8$ | 3 | | | | | | | | | | | |
| | JP Fleurian | 0 | 6$^3$ | | | | | | | 6 | J Hlasek | 6 | 6 | | | | | | |
| | K Curren | 2 | 7$^7$ | 6 | | | | | | | K Curren | 3 | 4 | | | | | | |
| | M Rosset | 6 | 6$^1$ | 1 | | K Curren | 6 | 3 | 6 | | | | | | | | | | |
| Q | D Engel | 6 | 5 | 6$^2$ | 3 | S Bruguera | 4 | 6 | 3 | | | | | | | | | | |
| 3 | S Bruguera | 2 | 7 | 7$^7$ | | | | | | | | | | | 6 | J Hlasek | 7$^7$ | 6$^5$ | 7$^7$ |
| 7 | A Volkov | 6 | 6 | | | | | | | | | | | | 7 | A Volkov | 6$^3$ | 7$^7$ | 6$^5$ |
| | G Raoux | 3 | 4 | | 7 | A Volkov | 6 | 6 | | | | | | | | | | | |
| | T Carbonell | 7 | 6 | | | T Carbonell | 3 | 4 | | | | | | | | | | | |
| | C Saceanu | 5 | 3 | | | | | | | 7 | A Volkov | 6 | 6$^9$ | 6 | | | | | |
| | N Kulti | 6 | 6 | | | | | | | 2 | K Nováček | 1 | 7$^{11}$ | 3 | | | | | |
| | C Caratti | 1 | 4 | | | N Kulti | 4 | 7$^7$ | 6$^2$ | | | | | | | | | | |
| | P Haarhuis | 2 | 6 | 3 | 2 | K Nováček | 6 | 6$^2$ | 7$^7$ | | | | | | | | | | |
| 2 | K Nováček | 6 | 1 | 6 | | | | | | | | | | | | | | | |