# 2021 Rio Tennis Classic – Singles

Carlos Berlocq was the defending champion but chose not to defend his title.
Kaichi Uchida won the title after defeating Nicolás Álvarez Varona 3–6, 6–3, 7–6$^{(7–3)}$ in the final.

## Seeds

* Thiago Seyboth Wild (quarterfinals)
* Nicolás Kicker (semifinals)
* Juan Pablo Ficovich (first round)
* Matheus Pucinelli de Almeida (withdrew)
* Roberto Cid Subervi (first round, retired)
* Orlando Luz (first round)
* Peđa Krstin (first round)
* Kaichi Uchida (champion)

## 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 | Final |
| 8 | Kaichi Uchida | 6 | 6 | | | | | |
| WC | Gabriel Décamps | 2 | 3 | | | | | |
| WC | Gabriel Décamps | 2 | 3 | 8 | Kaichi Uchida | 3 | 6 | 7$^7$ |
| | | | | | Nicolás Álvarez Varona | 6 | 3 | 6$^3$ |
| | Nicolás Álvarez Varona | 6 | 7 | | Nicolás Álvarez Varona | 6 | 3 | 6$^3$ |
| 2 | Nicolás Kicker | 2 | 5 | | | | | |

### 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 | T Seyboth Wild | 6 | 6 | | | | | | | | | | | | | | | |
| WC | Lorenzo Esquici | 2 | 0 | | 1 | T Seyboth Wild | 6 | 3 | 7 | | | | | | | | | |
| | J Nikles | 6 | 6 | | | J Nikles | 1 | 6 | 5 | | | | | | | | | |
| Q | L Castelnuovo | 2 | 4 | | | | | | | 1 | T Seyboth Wild | 4 | 1 | | | | | |
| | GA Olivieri | 5 | 6 | 6 | | | | | | 8 | K Uchida | 6 | 6 | | | | | |
| PR | G Clezar | 7 | 4 | 3 | | GA Olivieri | 6 | 3 | 1 | | | | | | | | | |
| | G Villanueva | 3 | 4 | | 8 | K Uchida | 3 | 6 | 6 | | | | | | | | | |
| 8 | K Uchida | 6 | 6 | | | | | | | | | | | | 8 | K Uchida | 6 | 6 |
| 3 | JP Ficovich | 6 | 1 | 2 | | | | | | | | | | | WC | G Décamps | 2 | 3 |
| | A Gómez | 4 | 6 | 6 | | A Gómez | 6 | 4 | 1 | | | | | | | | | |
| WC | G Décamps | 6 | 6 | | WC | G Décamps | 3 | 6 | 6 | | | | | | | | | |
| Q | N Barrientos | 1 | 4 | | | | | | | WC | G Décamps | 6 | 4 | 6 | | | | |
| Q | R Matos | 6 | 0 | 6 | | | | | | | D Dutra da Silva | 4 | 6 | 2 | | | | |
| WC | Wilson Leite | 4 | 6 | 2 | Q | R Matos | 3 | 0$^r$ | | | | | | | | | | |
| | D Dutra da Silva | 7$^8$ | 6 | | | D Dutra da Silva | 6 | 0 | | | | | | | | | | |
| 6 | O Luz | 6$^6$ | 4 | | | | | | | | | | | | | | | |

### 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 |
| 7 | P Krstin | 2 | 6$^6$ | | | | | | | | | | | | | | | |
| | L Darderi | 6 | 7$^8$ | | | L Darderi | 3 | 1 | | | | | | | | | | |
| | F Díaz Acosta | 3 | 6 | 3 | | N Álvarez Varona | 6 | 6 | | | | | | | | | | |
| | N Álvarez Varona | 6 | 4 | 6 | | | | | | | N Álvarez Varona | 6 | 6 | | | | | |
| | P Sakamoto | 6 | 4 | 6 | | | | | | LL | R Smith | 4 | 4 | | | | | |
| | Facundo Juárez | 4 | 6 | 4 | | P Sakamoto | 7$^{10}$ | 4 | 3 | | | | | | | | | |
| LL | Roy Smith | 6 | 7$^7$ | | LL | R Smith | 6$^8$ | 6 | 6 | | | | | | | | | |
| LL | F Zeballos | 4 | 6$^4$ | | | | | | | | | | | | | N Álvarez Varona | 6 | 7 |
| 5 | R Cid Subervi | 3 | 0$^r$ | | | | | | | | | | | | 2 | N Kicker | 2 | 5 |
| | B Bobrov | 6 | 1 | | | B Bobrov | 6$^4$ | 6 | 3 | | | | | | | | | |
| | MF Descotte | 6$^3$ | 4 | | Alt | M Alves | 7$^7$ | 3 | 6 | | | | | | | | | |
| Alt | M Alves | 7$^7$ | 6 | | | | | | | Alt | M Alves | 6 | 6$^4$ | 4 | | | | |
| Q | J Pereira | 2 | 7 | 4 | | | | | | 2 | N Kicker | 3 | 7$^7$ | 6 | | | | |
| SE | I Marcondes | 6 | 5 | 6 | SE | I Marcondes | 4 | 1 | | | | | | | | | | |
| | A González | 5 | 3 | | 2 | N Kicker | 6 | 6 | | | | | | | | | | |
| 2 | N Kicker | 7 | 6 | | | | | | | | | | | | | | | |