# 1991 OTB International Open – Men's singles

Ramesh Krishnan was the defending champion, but lost in the first round this year.
Michael Stich won the tournament, beating Emilio Sánchez in the final, 6–2, 6–4.

## Seeds

* Michael Stich (champion)
* Sergi Bruguera (quarterfinals)
* Emilio Sánchez (final)
* Andrei Cherkasov (quarterfinals)
* Alexander Volkov (quarterfinals)
* Horst Skoff (semifinals)
* Todd Woodbridge (quarterfinals)
* Francisco Clavet (semifinals)

## 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 | Final | Final | Final | Final |
| 1 | Michael Stich | 7 | 6 | | | | |
| 6 | Horst Skoff | 5 | 1 | | | | |
| 6 | Horst Skoff | 5 | 1 | 1 | Michael Stich | 6 | 6 |
| | | | | 3 | Emilio Sánchez | 2 | 4 |
| 3 | Emilio Sánchez | 7 | 6 | 3 | Emilio Sánchez | 2 | 4 |
| 8 | Francisco Clavet | 5 | 1 | | | | |

### Top 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 |
| 1 | M Stich | 7$^8$ | 6 | | | | | | | | | | | | | | | |
| | M Woodforde | 6$^6$ | 3 | | 1 | M Stich | 6 | 6 | | | | | | | | | | |
| | T Carbonell | 4 | 6 | 7 | | T Carbonell | 1 | 2 | | | | | | | | | | |
| | P Kühnen | 6 | 3 | 5 | | | | | | 1 | M Stich | 6 | 6 | | | | | |
| WC | A Gómez | 6 | 6 | | | | | | | 7 | T Woodbridge | 4 | 2 | | | | | |
| | J Eltingh | 4 | 0 | | WC | A Gómez | 7$^7$ | 4 | 5 | | | | | | | | | |
| | C Bergström | 1 | 2 | | 7 | T Woodbridge | 6$^4$ | 6 | 7 | | | | | | | | | |
| 7 | T Woodbridge | 6 | 6 | | | | | | | | | | | | 1 | M Stich | 7 | 6 |
| 4 | A Cherkasov | 6 | 6 | | | | | | | | | | | | 6 | H Skoff | 5 | 1 |
| | J Tarango | 2 | 3 | | 4 | A Cherkasov | 6 | 7 | | | | | | | | | | |
| | R Fromberg | 6 | 6 | | | R Fromberg | 2 | 5 | | | | | | | | | | |
| | J Arias | 4 | 3 | | | | | | | 4 | A Cherkasov | 7$^{10}$ | 3 | 6$^2$ | | | | |
| | R Krishnan | 3 | 4 | | | | | | | 6 | H Skoff | 6$^8$ | 6 | 7$^7$ | | | | |
| Q | C Adams | 6 | 6 | | Q | C Adams | 7 | 2 | 6$^3$ | | | | | | | | | |
| | W Ferreira | 3 | 7$^7$ | 2 | 6 | H Skoff | 5 | 6 | 7$^7$ | | | | | | | | | |
| 6 | H Skoff | 6 | 6$^4$ | 6 | | | | | | | | | | | | | | |

### 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 | Semifinals | Semifinals | Semifinals | Semifinals |
| 5 | A Volkov | 6 | 6 | | | | | | | | | | | | | | |
| | D Poliakov | 2 | 1 | | 5 | A Volkov | 0 | 7$^9$ | 7 | | | | | | | | |
| | C Pioline | 2 | 4 | | | J Sánchez | 6 | 6$^7$ | 5 | | | | | | | | |
| | J Sánchez | 6 | 6 | | | | | | | 5 | A Volkov | 1 | 5 | | | | |
| | G Raoux | 3 | 1$^d$ | | | | | | | 3 | E Sánchez | 6 | 7 | | | | |
| | B Wuyts | 6 | 2 | | | B Wuyts | 6$^5$ | 2 | | | | | | | | | |
| LL | D Adams | 4 | 4 | | 3 | E Sánchez | 7$^7$ | 6 | | | | | | | | | |
| 3 | E Sánchez | 6 | 6 | | | | | | | | | | | 3 | E Sánchez | 7 | 6 |
| 8 | F Clavet | 7 | 7$^7$ | | | | | | | | | | | 8 | F Clavet | 5 | 1 |
| Q | S Simian | 5 | 6$^4$ | | 8 | F Clavet | 6 | 6 | | | | | | | | | |
| Q | M Knowles | 6 | 7$^7$ | | Q | M Knowles | 3 | 0 | | | | | | | | | |
| Q | N Pereira | 4 | 6$^5$ | | | | | | | 8 | F Clavet | 6 | 6 | | | | |
| LL | Jason Netter | 3 | 2 | | | | | | | 2 | S Bruguera | 1 | 4 | | | | |
| | P Haarhuis | 6 | 6 | | | P Haarhuis | 4 | 6 | 5 | | | | | | | | |
| | J Stoltenberg | 6 | 2 | 3 | 2 | S Bruguera | 6 | 3 | 7 | | | | | | | | |
| 2 | S Bruguera | 4 | 6 | 6 | | | | | | | | | | | | | |