# 2021 Tennis Napoli Cup – Singles

Jozef Kovalík was the defending champion but chose not to defend his title.
Tallon Griekspoor won the title after defeating Andrea Pellegrino 6–3, 6–2 in the final.

## Seeds

* Stefano Travaglia (semifinals)
* Andrej Martin (second round)
* Yannick Hanfmann (second round)
* Tallon Griekspoor (champion)
* Zdeněk Kolář (second round)
* Alessandro Giannessi (first round, retired)
* Gian Marco Moroni (quarterfinals)
* Lorenzo Giustino (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

### Finals

| Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| 1 | Stefano Travaglia | 6 | 4 | 2 | | | | |
| 4 | Tallon Griekspoor | 2 | 6 | 6 | | | | |
| 4 | Tallon Griekspoor | 2 | 6 | 6 | 4 | Tallon Griekspoor | 6 | 6 |
| | | | | | | Andrea Pellegrino | 3 | 2 |
| | Andrea Pellegrino | 6 | 4 | | | Andrea Pellegrino | 3 | 2 |
| | Duje Ajduković | 2 | 1$^r$ | | | | | |

### 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 | Semifinals |
| 1 | S Travaglia | 7$^7$ | 6 | | | | | | | | | | | | | | | |
| | E Kırkın | 6$^3$ | 3 | | 1 | S Travaglia | 6 | 6 | | | | | | | | | | |
| | J de Jong | 3 | 4 | | | F Cobolli | 2 | 2 | | | | | | | | | | |
| | F Cobolli | 6 | 6 | | | | | | | 1 | S Travaglia | 7$^{10}$ | 7 | | | | | |
| | F Agamenone | 6 | 1 | 2 | | | | | | | A Vavassori | 6$^8$ | 5 | | | | | |
| | A Vavassori | 2 | 6 | 6 | | A Vavassori | 2 | 6 | 7$^7$ | | | | | | | | | |
| WC | M Arnaldi | 2 | 3 | | WC | M Arnaldi | 6 | 2 | 6$^3$ | | | | | | | | | |
| 6 | A Giannessi | 6 | 1$^r$ | | | | | | | | | | | 1 | S Travaglia | 6 | 4 | 2 |
| 4 | T Griekspoor | 6 | 0 | | | | | | | | | | | 4 | T Griekspoor | 2 | 6 | 6 |
| Q | J Ocleppo | 4 | 0$^r$ | | 4 | T Griekspoor | 3 | 7 | 6 | | | | | | | | | |
| | A Ritschard | 6 | 6 | | | A Ritschard | 6 | 5 | 1 | | | | | | | | | |
| | J Forejtek | 4 | 4 | | | | | | | 4 | T Griekspoor | 6 | 7$^7$ | | | | | |
| PR | F Baldi | 6 | 3 | 6 | | | | | | 7 | GM Moroni | 3 | 6$^1$ | | | | | |
| LL | P Tsitsipas | 4 | 6 | 4 | PR | F Baldi | 5 | 3 | | | | | | | | | | |
| Alt | M Zekić | 1 | 7$^7$ | 2 | 7 | GM Moroni | 7 | 6 | | | | | | | | | | |
| 7 | GM Moroni | 6 | 6$^2$ | 6 | | | | | | | | | | | | | | |

### 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 | Semifinals | Semifinals | Semifinals |
| 5 | Z Kolář | 6 | 6 | | | | | | | | | | | | | |
| | N Serdarušić | 4 | 4 | | 5 | Z Kolář | 4 | 7$^8$ | 2 | | | | | | | |
| Q | R Brancaccio | 7$^7$ | 4 | | Q | R Brancaccio | 6 | 6$^6$ | 6 | | | | | | | |
| Q | Bogdan Ionuț Apostol | 6$^1$ | 0$^r$ | | | | | | | Q | R Brancaccio | 5 | 6$^6$ | | | |
| WC | J Berrettini | 2 | 4 | | | | | | | | A Pellegrino | 7 | 7$^8$ | | | |
| | A Pellegrino | 6 | 6 | | | A Pellegrino | 6 | 6 | | | | | | | | |
| WC | L Nardi | 0 | 6 | 1 | 3 | Y Hanfmann | 3 | 3 | | | | | | | | |
| 3 | Y Hanfmann | 6 | 2 | 6 | | | | | | | | | | A Pellegrino | 6 | 4 |
| 8 | L Giustino | 6 | 1 | 1 | | | | | | | | | | D Ajduković | 2 | 1$^r$ |
| | R Bonadio | 3 | 6 | 6 | | R Bonadio | 6 | 1 | 6$^4$ | | | | | | | |
| | G Blancaneaux | 1 | 6 | 6$^4$ | | M Bašić | 4 | 6 | 7$^7$ | | | | | | | |
| | M Bašić | 6 | 2 | 7$^7$ | | | | | | | M Bašić | 4 | 4 | | | |
| | D Ajduković | 6 | 6 | | | | | | | | D Ajduković | 6 | 6 | | | |
| | E Furness | 4 | 4 | | | D Ajduković | 4 | 6 | 6 | | | | | | | |
| Q | Marco Miceli | 6 | 3 | 4 | 2 | A Martin | 6 | 3 | 3 | | | | | | | |
| 2 | A Martin | 4 | 6 | 6 | | | | | | | | | | | | |