# 1991 U.S. Pro Indoor – Singles

Pete Sampras was the defending champion.
Ivan Lendl won the title, defeating Sampras, 5–7, 6–4, 6–4, 3–6, 6–3 in the final.

## Seeds

* Ivan Lendl (champion)
* Pete Sampras (final)
* Brad Gilbert (semifinals)
* John McEnroe (semifinals)
* Jay Berger (second round)
* Jim Courier (second round)
* Michael Stich (quarterfinals)
* Tim Mayotte (second round)
* Petr Korda (quarterfinals)
* Derrick Rostagno (second round)
* Darren Cahill (third round)
* Mark Koevermans (second round)
* Wally Masur (third round)
* Paul Haarhuis (third round)
* Gary Muller (third round)
* Patrick McEnroe (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

| Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final | Final | Final | Final |
| 1 | Ivan Lendl | 6 | 3 | 6 | | | | | | | |
| 3 | Brad Gilbert | 4 | 6 | 4 | | | | | | | |
| 3 | Brad Gilbert | 4 | 6 | 4 | 1 | Ivan Lendl | 5 | 6 | 6 | 3 | 6 |
| | | | | | 2 | Pete Sampras | 7 | 4 | 4 | 6 | 3 |
| 4/WC | John McEnroe | 2 | 4 | | 2 | Pete Sampras | 7 | 4 | 4 | 6 | 3 |
| 2 | Pete Sampras | 6 | 6 | | | | | | | | |

### Top half
#### Section 1

| 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 |
| | | | | | 1 | I Lendl | 6 | 7 | | | | | | | | | |
| Q | D Goldie | 4 | 6$^7$ | | | G Raoux | 1 | 5 | | | | | | | | | |
| | G Raoux | 6 | 7$^9$ | | | | | | | 1 | I Lendl | 7$^7$ | 6 | | | | |
| | R Furlan | 4 | 7 | 6 | | | | | | 15 | G Muller | 6$^5$ | 3 | | | | |
| | V Paloheimo | 6 | 5 | 4 | | R Furlan | 7$^7$ | 3 | 4 | | | | | | | | |
| | | | | | 15 | G Muller | 6$^5$ | 6 | 6 | | | | | | | | |
| | | | | | | | | | | | | | | 1 | I Lendl | 6 | 7$^9$ |
| | | | | | | | | | | | | | | 7 | M Stich | 2 | 6$^7$ |
| | | | | | 10 | D Rostagno | 5 | 3 | | | | | | | | | |
| Q | G Stafford | 2 | 2 | | Q | C Adams | 7 | 6 | | | | | | | | | |
| Q | C Adams | 6 | 6 | | | | | | | Q | C Adams | 4 | 4 | | | | |
| Q | J Tarango | 5 | 4 | | | | | | | 7 | M Stich | 6 | 6 | | | | |
| WC | C Caratti | 7 | 6 | | WC | C Caratti | 2 | 4 | | | | | | | | | |
| | | | | | 7 | M Stich | 6 | 6 | | | | | | | | | |

#### Section 2

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 3 | B Gilbert | 6 | 6 | | | | | | | | | | |
| | T Carbonell | 6 | 6 | | | T Carbonell | 3 | 3 | | | | | | | | | | |
| WC | G Bloom | 1 | 1 | | | | | | 3 | B Gilbert | 7$^7$ | 6 | | | | | | |
| | U Riglewski | 6 | 6$^3$ | 6 | | | | | 14 | P Haarhuis | 6$^3$ | 1 | | | | | | |
| Q | G Layendecker | 3 | 7$^7$ | 0 | | U Riglewski | 1 | 3 | | | | | | | | | | |
| | | | | | 14 | P Haarhuis | 6 | 6 | | | | | | | | | | |
| | | | | | | | | | | | | | | 3 | B Gilbert | 4 | 6 | 6 |
| | | | | | | | | | | | | | | | K Curren | 6 | 3 | 0 |
| | | | | | 11 | D Cahill | 6 | 6 | | | | | | | | | | |
| | T Högstedt | 6 | 6 | | | T Högstedt | 4 | 2 | | | | | | | | | | |
| | R Krishnan | 3 | 1 | | | | | | 11 | D Cahill | 7$^9$ | 3 | 6$^2$ | | | | | |
| | M Kratzmann | 3 | 7$^7$ | 4 | | | | | | K Curren | 6$^7$ | 6 | 7$^7$ | | | | | |
| | K Curren | 6 | 6$^4$ | 6 | | K Curren | 6 | 6 | | | | | | | | | | |
| | | | | | 5 | J Berger | 1 | 2 | | | | | | | | | | |

### Bottom half
#### Section 3

| 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 |
| | | | 6 | J Courier | 2 | 4 | | | | | | | | | | |
| J Grabb | 6 | 6 | | J Grabb | 6 | 6 | | | | | | | | | | |
| P Kühnen | 4 | 4 | | | | | | | J Grabb | 7$^7$ | 1 | 3 | | | | |
| A Rahunen | 7$^{13}$ | 7 | | | | | | | A Rahunen | 6$^3$ | 6 | 6 | | | | |
| G Connell | 6$^{11}$ | 5 | | A Rahunen | 6 | 6 | | | | | | | | | | |
| | | | 12 | M Koevermans | 1 | 2 | | | | | | | | | | |
| | | | | | | | | | | | | | | A Rahunen | 5 | 3 |
| | | | | | | | | | | | | | 4/WC | J McEnroe | 7 | 6 |
| | | | 13 | W Masur | 4 | 7$^7$ | 7$^7$ | | | | | | | | | |
| C van Rensburg | 6 | 6 | | C van Rensburg | 6 | 6$^1$ | 6$^5$ | | | | | | | | | |
| B Pearce | 2 | 1 | | | | | | 13 | W Masur | 6$^2$ | 4 | | | | | |
| A Mronz | 6 | 6 | | | | | | 4/WC | J McEnroe | 7$^7$ | 6 | | | | | |
| H de la Peña | 2 | 2 | | A Mronz | 1 | 2 | | | | | | | | | | |
| | | | 4/WC | J McEnroe | 6 | 6 | | | | | | | | | | |

#### Section 4

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | | | 8 | T Mayotte | 4 | 2 | | | | | | | | |
| | J-P Fleurian | 5 | 4 | | Q | W Ferreira | 6 | 6 | | | | | | | | |
| Q | W Ferreira | 7 | 6 | | | | | | Q | W Ferreira | 5 | 6$^3$ | | | | |
| | J Yzaga | 6 | 6 | | | | | | 9 | P Korda | 7 | 7$^7$ | | | | |
| | A Järryd | 3 | 3 | | | J Yzaga | 4 | 3 | | | | | | | | |
| | | | | | 9 | P Korda | 6 | 6 | | | | | | | | |
| | | | | | | | | | | | | | 9 | P Korda | 4 | 0 |
| | | | | | | | | | | | | | 2 | P Sampras | 6 | 6 |
| | | | | | 16/WC | P McEnroe | 0 | 3 | | | | | | | | |
| | A Antonitsch | 6$^1$ | 6 | 0 | | M Washington | 6 | 6 | | | | | | | | |
| | M Washington | 7$^7$ | 4 | 6 | | | | | | M Washington | 3 | 6$^7$ | | | | |
| | M Šrejber | 6 | 6$^2$ | 6 | | | | | 2 | P Sampras | 6 | 7$^9$ | | | | |
| | S Davis | 4 | 7$^7$ | 3 | | M Šrejber | 2 | 5 | | | | | | | | |
| | | | | | 2 | P Sampras | 6 | 7 | | | | | | | | |