# 2021 Open Città della Disfida – Singles

Gianluca Mager was the defending champion but chose not to defend his title.
Giulio Zeppieri won the title after defeating Flavio Cobolli 6–1, 3–6, 6–3 in the final.

## Seeds

* Andrej Martin (second round)
* Juan Manuel Cerúndolo (first round, retired)
* Jay Clarke (first round)
* Tim van Rijthoven (second round)
* Matteo Viola (first round)
* Jack Draper (first round)
* Riccardo Bonadio (first round)
* Tseng Chun-hsin (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 | Semifinals | Final | Final | Final | Final |
| | Thiago Agustín Tirante | 1 | 6 | 5 | | | | |
| | Flavio Cobolli | 6 | 1 | 7 | | | | |
| | Flavio Cobolli | 6 | 1 | 7 | Flavio Cobolli | 1 | 6 | 3 |
| | | | | | Giulio Zeppieri | 6 | 3 | 6 |
| 8 | Tseng Chun-hsin | 6 | 2 | 3 | Giulio Zeppieri | 6 | 3 | 6 |
| | Giulio Zeppieri | 3 | 6 | 6 | | | | |

### 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 |
| 1 | A Martin | 4 | 6 | 6 | | | | | | | | | | | | |
| WC | J Berrettini | 6 | 2 | 1 | 1 | A Martin | 6$^3$ | 2 | | | | | | | | |
| | TA Tirante | 6 | 4 | 6 | | TA Tirante | 7$^7$ | 6 | | | | | | | | |
| | P Chrysochos | 1 | 6 | 2 | | | | | | TA Tirante | 6 | 6 | | | | |
| Alt | F Forti | 2 | 2 | | | | | | Q | N Álvarez | 2 | 2 | | | | |
| | R Quiroz | 6 | 6 | | | R Quiroz | 5 | 4 | | | | | | | | |
| Q | N Álvarez | 4 | 7$^7$ | 7 | Q | N Álvarez | 7 | 6 | | | | | | | | |
| 7 | R Bonadio | 6 | 6$^5$ | 5 | | | | | | | | | TA Tirante | 1 | 6 | 5 |
| 4 | T van Rijthoven | 7 | 6 | | | | | | | | | | F Cobolli | 6 | 1 | 7 |
| WC | Emiliano Maggioli | 5 | 4 | | 4 | T van Rijthoven | 1 | 2 | | | | | | | | |
| | P Kotov | 2 | 6 | 2 | | F Cobolli | 6 | 6 | | | | | | | | |
| | F Cobolli | 6 | 4 | 6 | | | | | | F Cobolli | 6 | 6 | | | | |
| PR | Jeremy Jahn | 1$^r$ | | | | | | | | A Dougaz | 3 | 3 | | | | |
| | P Krstin | 5 | | | | P Krstin | 2 | 2 | | | | | | | | |
| | A Dougaz | 6 | 6 | | | A Dougaz | 6 | 6 | | | | | | | | |
| 6 | J Draper | 3 | 2 | | | | | | | | | | | | | |

### 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 | Semifinals |
| 8 | C-h Tseng | 6 | 0 | | | | | | | | | | | | | | | | |
| Q | R Harrison | 1 | 0$^r$ | | 8 | C-h Tseng | 5 | 6 | 6 | | | | | | | | | | |
| WC | L Nardi | 6 | 6 | | WC | L Nardi | 7 | 2 | 4 | | | | | | | | | | |
| | M Jaziri | 3 | 1 | | | | | | | 8 | C-h Tseng | 6 | 6 | | | | | | |
| | P Sakamoto | 6$^4$ | 6$^3$ | | | | | | | Q | A Vavassori | 4 | 4 | | | | | | |
| | N Mejía | 7$^7$ | 7$^7$ | | | N Mejía | 3 | 6$^4$ | | | | | | | | | | | |
| Q | A Vavassori | 6 | 6 | | Q | A Vavassori | 6 | 7$^7$ | | | | | | | | | | | |
| 3 | J Clarke | 3 | 4 | | | | | | | | | | | | 8 | C-h Tseng | 6 | 2 | 3 |
| 5 | M Viola | 2 | 5 | | | | | | | | | | | | | G Zeppieri | 3 | 6 | 6 |
| Q | C Rodríguez | 6 | 7 | | Q | C Rodríguez | 4 | 4 | | | | | | | | | | | |
| | J Ocleppo | 6 | 6 | | | J Ocleppo | 6 | 6 | | | | | | | | | | | |
| | J Sels | 4 | 3 | | | | | | | | J Ocleppo | 7 | 3 | 2 | | | | | |
| | G Zeppieri | 7 | 6 | | | | | | | | G Zeppieri | 5 | 6 | 6 | | | | | |
| | T Skatov | 5 | 0 | | | G Zeppieri | 6 | 6 | | | | | | | | | | | |
| | A Arnaboldi | 6 | 2 | 5 | | A Arnaboldi | 3 | 2 | | | | | | | | | | | |
| 2 | JM Cerúndolo | 1 | 6 | 2$^r$ | | | | | | | | | | | | | | | |