# 1991 Donnay Indoor Championships – Singles

Boris Becker was the defending champion, but retired from his semifinals match this year.
Guy Forget won the title, defeating Andrei Cherkasov 6–3, 7–5, 3–6, 7–6 in the final.

## Seeds

* Boris Becker (semifinals, retired)
* Stefan Edberg (semifinals)
* Andre Agassi (first round)
* Guy Forget (champion)
* Jonas Svensson (first round)
* Andrei Chesnokov (quarterfinals)
* Michael Chang (quarterfinals)
* Jakob Hlasek (quarterfinals)

## 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 | Final |
| 1 | Boris Becker | 6 | 3 | 2$^r$ | | | | | | |
| WC | Andrei Cherkasov | 2 | 6 | 2 | | | | | | |
| WC | Andrei Cherkasov | 2 | 6 | 2 | WC | Andrei Cherkasov | 3 | 5 | 6 | 6 |
| | | | | | 4 | Guy Forget | 6 | 7 | 3 | 7 |
| 4 | Guy Forget | 3 | 6 | 6 | 4 | Guy Forget | 6 | 7 | 3 | 7 |
| 2 | Stefan Edberg | 6 | 0 | 3 | | | | | | |

### 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 | Semifinals |
| 1 | B Becker | 6 | 3 | 6 | | | | | | | | | | | | | |
| | A Volkov | 4 | 6 | 3 | 1 | B Becker | 7 | 7 | | | | | | | | | |
| Q | E Jelen | 7 | 6 | | Q | E Jelen | 6 | 6 | | | | | | | | | |
| Q | S Doseděl | 6 | 3 | | | | | | 1 | B Becker | 7 | 6 | | | | | |
| Q | A Boetsch | 6 | 2 | 6 | | | | | 7 | M Chang | 5 | 1 | | | | | |
| | H Skoff | 4 | 6 | 4 | Q | A Boetsch | 3 | 2 | | | | | | | | | |
| | T Woodbridge | 4 | 3 | | 7 | M Chang | 6 | 6 | | | | | | | | | |
| 7 | M Chang | 6 | 6 | | | | | | | | | | 1 | B Becker | 6 | 3 | 2$^r$ |
| 3 | A Agassi | 3 | 6 | | | | | | | | | | WC | A Cherkasov | 2 | 6 | 2 |
| Q | C Saceanu | 6 | 7 | | Q | C Saceanu | 4 | 2 | | | | | | | | | |
| WC | A Cherkasov | 6 | 6 | | WC | A Cherkasov | 6 | 6 | | | | | | | | | |
| | J Aguilera | 2 | 2 | | | | | | WC | A Cherkasov | 7 | 6 | | | | | |
| | H Leconte | 7 | 4 | 2 | | | | | 6 | A Chesnokov | 5 | 1 | | | | | |
| | G Prpić | 6 | 6 | 6 | | G Prpić | 4 | 6 | | | | | | | | | |
| LL | C Bergström | 6 | 4 | 4 | 6 | A Chesnokov | 6 | 7 | | | | | | | | | |
| 6 | A Chesnokov | 3 | 6 | 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 | Semifinals |
| 5 | J Svensson | 0 | 4 | | | | | | | | | | | | | | | |
| | M Rosset | 6 | 6 | | | M Rosset | 6 | 6 | | | | | | | | | | |
| | C-U Steeb | 2 | 5 | | | R Agénor | 4 | 3 | | | | | | | | | | |
| | R Agénor | 6 | 7 | | | | | | | | M Rosset | 2 | 5 | | | | | |
| WC | E Masso | 6 | 6 | 6 | | | | | | 4 | G Forget | 6 | 7 | | | | | |
| | R Fromberg | 3 | 7 | 3 | WC | E Masso | 1 | 2 | | | | | | | | | | |
| | A Mansdorf | 6 | 3 | 3 | 4 | G Forget | 6 | 6 | | | | | | | | | | |
| 4 | G Forget | 4 | 6 | 6 | | | | | | | | | | 4 | G Forget | 3 | 6 | 6 |
| 8 | J Hlasek | 6 | 6 | | | | | | | | | | | 2 | S Edberg | 6 | 0 | 3 |
| | M Larsson | 3 | 2 | | 8 | J Hlasek | 6 | 7 | | | | | | | | | | |
| | M Wilander | 6 | 7 | | | M Wilander | 1 | 5 | | | | | | | | | | |
| | O Camporese | 4 | 6 | | | | | | | 8 | J Hlasek | 1 | 2 | | | | | |
| | K Nováček | 6 | 6 | 3 | | | | | | 2 | S Edberg | 6 | 6 | | | | | |
| WC | P Cash | 2 | 7 | 6 | WC | P Cash | 6 | 1 | 4 | | | | | | | | | |
| | M Gustafsson | 0 | 4 | | 2 | S Edberg | 3 | 6 | 6 | | | | | | | | | |
| 2 | S Edberg | 6 | 6 | | | | | | | | | | | | | | | |