# 2021 Internazionali di Tennis Città di Forlì – Singles

Lorenzo Musetti was the defending champion but chose not to defend his title.
Mats Moraing won the title after defeating Quentin Halys 3–6, 6–1, 7–5 in the final.

## Seeds

* Tallon Griekspoor (first round)
* Alessandro Giannessi (first round)
* Paolo Lorenzi (first round)
* Steven Diez (quarterfinals)
* Cem İlkel (first round)
* Robin Haase (first round)
* Tomás Martín Etcheverry (semifinals)
* Quentin Halys (final)

## 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 | Quentin Halys | 7$^7$ | 6 | | | | | |
| | Gastão Elias | 6$^4$ | 4 | | | | | |
| | Gastão Elias | 6$^4$ | 4 | 8 | Quentin Halys | 6 | 1 | 5 |
| | | | | | Mats Moraing | 3 | 6 | 7 |
| 7 | Tomás Martín Etcheverry | 3 | 5 | | Mats Moraing | 3 | 6 | 7 |
| | Mats Moraing | 6 | 7 | | | | | |

### 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 | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | T Griekspoor | 6 | 1 | 5 | | | | | | | | | | | | | |
| Q | F Forti | 4 | 6 | 7 | Q | F Forti | 6 | 6 | | | | | | | | | |
| Q | Lucas Gerch | 7$^8$ | 3 | 6 | Q | L Gerch | 4 | 4 | | | | | | | | | |
| Q | TA Tirante | 6$^6$ | 6 | 3 | | | | | | Q | F Forti | 5 | 3 | | | | |
| | F Baldi | 3 | 5 | | | | | | | 8 | Q Halys | 7 | 6 | | | | |
| | E Benchetrit | 6 | 7 | | | E Benchetrit | 4 | 5 | | | | | | | | | |
| | J Lenz | 3 | 3 | | 8 | Q Halys | 6 | 7 | | | | | | | | | |
| 8 | Q Halys | 6 | 6 | | | | | | | | | | | 8 | Q Halys | 7$^7$ | 6 |
| 3 | P Lorenzi | 3 | 4 | | | | | | | | | | | | G Elias | 6$^4$ | 4 |
| Alt | R Brancaccio | 6 | 6 | | Alt | R Brancaccio | 5 | 6 | 6 | | | | | | | | |
| | D Ajduković | 7$^7$ | 5 | 7$^7$ | | D Ajduković | 7 | 4 | 3 | | | | | | | | |
| WC | F Passaro | 6$^2$ | 7 | 6$^4$ | | | | | | Alt | R Brancaccio | 2 | 3 | | | | |
| | G Elias | 6 | 6 | | | | | | | | G Elias | 6 | 6 | | | | |
| PR | V Galović | 3 | 2 | | | G Elias | 6 | 7$^9$ | | | | | | | | | |
| Alt | O Luz | 7 | 3 | 7 | Alt | O Luz | 4 | 6$^7$ | | | | | | | | | |
| 5 | C İlkel | 5 | 6 | 5 | | | | | | | | | | | | | |

### 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 | TM Etcheverry | 6 | 6 | | | | | | | | | | | | | | | |
| | M Jaziri | 4 | 2 | | 7 | TM Etcheverry | 6 | 4 | 6 | | | | | | | | | |
| WC | F Cobolli | 6 | 7 | | WC | F Cobolli | 4 | 6 | 2 | | | | | | | | | |
| | G Zeppieri | 0 | 5 | | | | | | | 7 | TM Etcheverry | 4 | 6 | 6 | | | | |
| Q | S Fanselow | 2 | 2 | | | | | | | 4 | S Diez | 6 | 3 | 2 | | | | |
| | C Ugo Carabelli | 6 | 6 | | | C Ugo Carabelli | 2 | 6$^9$ | | | | | | | | | | |
| | A Arnaboldi | 0$^r$ | | | 4 | S Diez | 6 | 7$^{11}$ | | | | | | | | | | |
| 4 | S Diez | 5 | | | | | | | | | | | | | 7 | TM Etcheverry | 3 | 5 |
| 6 | R Haase | 3 | 1 | | | | | | | | | | | | | M Moraing | 6 | 7 |
| | M Moraing | 6 | 6 | | | M Moraing | 3 | 6 | 6 | | | | | | | | | |
| | I Sijsling | 6 | 7$^7$ | | | I Sijsling | 6 | 4 | 2 | | | | | | | | | |
| | A Pellegrino | 2 | 6$^5$ | | | | | | | | M Moraing | 6 | 6 | | | | | |
| | P Cachin | 4 | 6 | 6 | | | | | | WC | J Berrettini | 3 | 4 | | | | | |
| | H Grenier | 6 | 4 | 3 | | P Cachin | 6$^4$ | 7$^7$ | 4 | | | | | | | | | |
| WC | J Berrettini | 6 | 7$^7$ | | WC | J Berrettini | 7$^7$ | 6$^4$ | 6 | | | | | | | | | |
| 2 | A Giannessi | 1 | 6$^0$ | | | | | | | | | | | | | | | |