# 2021 Serbia Open – Men's singles

Matteo Berrettini defeated Aslan Karatsev in the final, 6–1, 3–6, 7–6$^{(7–0)}$ to win the men's singles tennis title at the 2021 Serbia Open.
Andreas Seppi was the reigning champion from when the event was last held in 2012, but he decided not to participate this year.

## Seeds

The top four seeds received a bye into the second round.
* Novak Djokovic (semifinals)
* Matteo Berrettini (champion)
* Aslan Karatsev (final)
* Dušan Lajović (second round)
* Filip Krajinović (quarterfinals)
* Márton Fucsovics (withdrew)
* John Millman (second round)
* Miomir Kecmanović (quarterfinals)
* Laslo Đere (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 | Final |
| 1 | Novak Djokovic | 5 | 6 | 4 | | | | | |
| 3 | Aslan Karatsev | 7 | 4 | 6 | | | | | |
| 3 | Aslan Karatsev | 7 | 4 | 6 | 3 | Aslan Karatsev | 1 | 6 | 6$^0$ |
| | | | | | 2 | Matteo Berrettini | 6 | 3 | 7$^7$ |
| LL | Taro Daniel | 1 | 7$^7$ | 0 | 2 | Matteo Berrettini | 6 | 3 | 7$^7$ |
| 2 | Matteo Berrettini | 6 | 6$^5$ | 6 | | | | | |

### 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 | N Djokovic | 6 | 6 | | | | | | | | | | |
| | S-w Kwon | 6 | 7 | | | S-w Kwon | 1 | 3 | | | | | | | | | | |
| LL | R Carballés Baena | 3 | 5 | | | | | | | 1 | N Djokovic | 6 | 6 | | | | | |
| Q | A Rinderknech | 6 | 7 | | | | | | | 8 | M Kecmanović | 1 | 3 | | | | | |
| | JI Londero | 1 | 5 | | Q | A Rinderknech | 3 | 6 | 3 | | | | | | | | | |
| Q | F Bagnis | 6$^5$ | 6$^4$ | | 8 | M Kecmanović | 6 | 3 | 6 | | | | | | | | | |
| 8 | M Kecmanović | 7$^7$ | 7$^7$ | | | | | | | | | | | 1 | N Djokovic | 5 | 6 | 4 |
| | | | | | | | | | | | | | | 3 | A Karatsev | 7 | 4 | 6 |
| | | | | | 3 | A Karatsev | 6 | 4 | 7$^7$ | | | | | | | | | |
| | S Korda | 5 | 6 | 6$^5$ | | A Bedene | 3 | 6 | 6$^5$ | | | | | | | | | |
| | A Bedene | 7 | 1 | 7$^7$ | | | | | | 3 | A Karatsev | 6 | 6 | | | | | |
| Q | F Cerúndolo | 6 | 6$^5$ | 6$^6$ | | | | | | Q | G Mager | 3 | 4 | | | | | |
| | A Popyrin | 4 | 7$^7$ | 7$^8$ | | A Popyrin | 5 | 2 | | | | | | | | | | |
| Q | G Mager | 6 | 6 | | Q | G Mager | 7 | 6 | | | | | | | | | | |
| 9 | L Đere | 4 | 3 | | | | | | | | | | | | | | | |

### 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 |
| 7 | J Millman | 7 | 6 | | | | | | | | | | | | | | | | |
| WC | D Petrović | 5 | 4 | | 7 | J Millman | 6 | 2 | 3 | | | | | | | | | | |
| LL | J Sousa | 5 | 3 | | LL | T Daniel | 3 | 6 | 6 | | | | | | | | | | |
| LL | T Daniel | 7 | 6 | | | | | | | LL | T Daniel | 4 | 6 | 7 | | | | | |
| | R Berankis | 4 | 6 | 1 | | | | | | | F Delbonis | 6 | 1 | 5 | | | | | |
| | F Delbonis | 6 | 3 | 6 | | F Delbonis | 6 | 2 | 6 | | | | | | | | | | |
| | | | | | 4 | D Lajović | 3 | 6 | 4 | | | | | | | | | | |
| | | | | | | | | | | | | | | | LL | T Daniel | 1 | 7$^7$ | 0 |
| 5 | F Krajinović | 7 | 5 | 6 | | | | | | | | | | | 2 | M Berrettini | 6 | 6$^5$ | 6 |
| | S Travaglia | 5 | 7 | 3 | 5 | F Krajinović | 6 | 6 | | | | | | | | | | | |
| WC | N Milojević | 6 | 6 | | WC | N Milojević | 1 | 1 | | | | | | | | | | | |
| | F Coria | 4 | 0 | | | | | | | 5 | F Krajinović | 4 | 4 | | | | | | |
| WC | V Troicki | 1 | 4 | | | | | | | 2 | M Berrettini | 6 | 6 | | | | | | |
| | M Cecchinato | 6 | 6 | | | M Cecchinato | 4 | 3 | | | | | | | | | | | |
| | | | | | 2 | M Berrettini | 6 | 6 | | | | | | | | | | | |

## Qualifying
### Seeds

* Gianluca Mager (qualified)
* Facundo Bagnis (qualified)
* Roberto Carballés Baena (qualifying competition, lucky loser)
* João Sousa (qualifying competition, lucky loser)
* Yūichi Sugita (first round)
* Daniel Elahi Galán (first round)
* Francisco Cerúndolo (qualified)
* Taro Daniel (qualifying competition, lucky loser)

### Qualifiers

* Gianluca Mager
* Facundo Bagnis
* Francisco Cerúndolo
* Arthur Rinderknech

### Lucky losers

* Roberto Carballés Baena
* João Sousa
* Taro Daniel

### Qualifying draw
#### First qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 1 | Gianluca Mager | 4 | 7$^7$ | 6 | | | | | |
| | Benjamin Bonzi | 6 | 6$^1$ | 3 | | | | | |
| | Benjamin Bonzi | 6 | 6$^1$ | 3 | 1 | Gianluca Mager | 6 | 4 | 6 |
| | | | | | 8 | Taro Daniel | 1 | 6 | 4 |
| WC | Marko Miladinović | 1 | 2 | | 8 | Taro Daniel | 1 | 6 | 4 |
| 8 | Taro Daniel | 6 | 6 | | | | | | |

#### Second qualifier

| First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 2 | Facundo Bagnis | 6 | 6 | | | | |
| | Evgeny Donskoy | 3 | 2 | | | | |
| | Evgeny Donskoy | 3 | 2 | 2 | Facundo Bagnis | 6 | 6 |
| | | | | WC | Hamad Međedović | 4 | 2 |
| WC | Hamad Međedović | 7$^7$ | 7$^7$ | WC | Hamad Međedović | 4 | 2 |
| 6 | Daniel Elahi Galán | 6$^4$ | 6$^5$ | | | | |

#### Third qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 3 | Roberto Carballés Baena | 7$^7$ | 2 | 0 | | | | |
| | Damir Džumhur | 6$^2$ | 6 | 0$^r$ | | | | |
| | Damir Džumhur | 6$^2$ | 6 | 0$^r$ | 3 | Roberto Carballés Baena | 6$^6$ | 4 |
| | | | | | 7 | Francisco Cerúndolo | 7$^8$ | 6 |
| | Jozef Kovalík | 5 | 4 | | 7 | Francisco Cerúndolo | 7$^8$ | 6 |
| 7 | Francisco Cerúndolo | 7 | 6 | | | | | |

#### Fourth qualifier

| First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 4 | João Sousa | 6 | 6 | | | | |
| | Brandon Nakashima | 4 | 2 | | | | |
| | Brandon Nakashima | 4 | 2 | 4 | João Sousa | 5 | 4 |
| | | | | | Arthur Rinderknech | 7 | 6 |
| | Arthur Rinderknech | 6 | 6 | | Arthur Rinderknech | 7 | 6 |
| 5 | Yūichi Sugita | 1 | 2 | | | | |