# 1991 U.S. Men's Clay Court Championships – Singles

David Wheaton was the defending champion, but lost in the quarterfinals this year.
Jaime Yzaga won the title, defeating Jimmy Arias 6–3, 7–5 in the final.

## Seeds

A champion seed is indicated in bold text while text in italics indicates the round in which that seed was eliminated.
* Michael Chang (quarterfinals)
* Derrick Rostagno (first round)
* David Wheaton (quarterfinals)
* Richey Reneberg (quarterfinals)
* Jimmy Arias (final)
* Scott Davis (first round)
* Jaime Yzaga (champion)
* David Pate (first 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
| 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 | Final | Final | Final | Final |
| 1 | M Chang | 6 | 7 | | | | | | | | | | | | | | | | | | | | |
| | N Kroon | 0 | 5 | | 1 | M Chang | 6$^5$ | 6 | 7 | | | | | | | | | | | | | | |
| | B Shelton | 6 | 6 | | | B Shelton | 7$^7$ | 4 | 5 | | | | | | | | | | | | | | |
| | S Pescosolido | 2 | 2 | | | | | | | 1 | M Chang | 6$^0$ | 1 | | | | | | | | | | |
| | A Sznajder | 1 | 6 | 4 | | | | | | 7 | J Yzaga | 7$^7$ | 6 | | | | | | | | | | |
| Q | J Brown | 6 | 3 | 6 | Q | J Brown | 4 | 4 | | | | | | | | | | | | | | | |
| | C Garner | 6$^6$ | 3 | | 7 | J Yzaga | 6 | 6 | | | | | | | | | | | | | | | |
| 7 | J Yzaga | 7$^8$ | 6 | | | | | | | | | | | | 7 | J Yzaga | 7 | 6 | | | | | |
| 3 | D Wheaton | 6 | 6 | | | | | | | | | | | | | M Washington | 5 | 2 | | | | | |
| | C Adams | 4 | 3 | | 3 | D Wheaton | 6 | 6 | | | | | | | | | | | | | | | |
| WC | J Pugh | 1 | 3 | | | P Korda | 3 | 4 | | | | | | | | | | | | | | | |
| | P Korda | 6 | 6 | | | | | | | 3 | D Wheaton | 7$^7$ | 1 | 2 | | | | | | | | | |
| WC | R Leach | 1 | 6$^4$ | | | | | | | | M Washington | 6$^3$ | 6 | 6 | | | | | | | | | |
| | M Washington | 6 | 7$^7$ | | | M Washington | 6 | 6 | | | | | | | | | | | | | | | |
| | C Saceanu | 6 | 3 | 6 | | C Saceanu | 3 | 4 | | | | | | | | | | | | | | | |
| 6 | S Davis | 1 | 6 | 0 | | | | | | | | | | | | | | | | 7 | Jaime Yzaga | 6 | 7 |
| 5 | J Arias | 6 | 6 | | | | | | | | | | | | | | | | | 5 | Jimmy Arias | 3 | 5 |
| | T Högstedt | 3 | 3 | | 5 | J Arias | 6 | 6 | | | | | | | | | | | | | | | |
| | J Tarango | 4 | 2 | | | D Pérez | 1 | 4 | | | | | | | | | | | | | | | |
| | D Pérez | 6 | 6 | | | | | | | 5 | J Arias | 6 | 6 | | | | | | | | | | |
| WC | M Pernfors | 4 | 4 | | | | | | | 4 | R Reneberg | 4 | 2 | | | | | | | | | | |
| Q | M Wostenholme | 6 | 6 | | Q | M Wostenholme | 6 | 0 | 3 | | | | | | | | | | | | | | |
| Q | R Viver | 4 | 5 | | 4 | R Reneberg | 4 | 6 | 6 | | | | | | | | | | | | | | |
| 4 | R Reneberg | 6 | 7 | | | | | | | | | | | | 5 | J Arias | 3 | 6 | 7 | | | | |
| 8 | D Pate | 6 | 3 | 6$^3$ | | | | | | | | | | | Q | J Frana | 6 | 3 | 5 | | | | |
| | B Pearce | 3 | 6 | 7$^7$ | | B Pearce | 4 | 2 | | | | | | | | | | | | | | | |
| | B Garrow | 6$^3$ | 3 | | Q | J Frana | 6 | 6 | | | | | | | | | | | | | | | |
| Q | J Frana | 7$^7$ | 6 | | | | | | | Q | J Frana | 6 | | | | | | | | | | | |
| | D Nargiso | 6 | 7$^7$ | | | | | | | | P Arraya | 4 | r | | | | | | | | | | |
| | K Evernden | 2 | 6$^3$ | | | D Nargiso | 6 | 4 | 6$^3$ | | | | | | | | | | | | | | |
| | P Arraya | 7$^7$ | 6 | | | P Arraya | 2 | 6 | 7$^7$ | | | | | | | | | | | | | | |
| 2 | D Rostagno | 6$^3$ | 3 | | | | | | | | | | | | | | | | | | | | |