# 2021 Astana Open – Men's singles

John Millman was the defending champion, but lost in the quarterfinals to James Duckworth.
Kwon Soon-woo won his first ATP Tour title, defeating Duckworth in the final, 7–6$^{(8–6)}$, 6–3. Kwon became the first South Korean player to win a title at ATP Tour level since Lee Hyung-taik in the 2003 Sydney tournament.

## Seeds

The top four seeds received a bye into the second round.
* Aslan Karatsev (second round)
* Alexander Bublik (semifinals)
* Dušan Lajović (second round)
* Filip Krajinović (second round)
* John Millman (quarterfinals)
* Benoît Paire (first round)
* Laslo Đere (quarterfinals)
* Ilya Ivashka (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 |
| 8 | Ilya Ivashka | 3 | 6$^4$ | | | | |
| | James Duckworth | 6 | 7$^7$ | | | | |
| | James Duckworth | 6 | 7$^7$ | | James Duckworth | 6$^6$ | 3 |
| | | | | | Kwon Soon-woo | 7$^8$ | 6 |
| | Kwon Soon-woo | 3 | 7 | 6 | Kwon Soon-woo | 7$^8$ | 6 |
| 2 | Alexander Bublik | 6 | 5 | 3 | | | |

### 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 | A Karatsev | 6$^6$ | 4 | | | | | | | | | | |
| | E Ruusuvuori | 6 | 0 | | | E Ruusuvuori | 7$^8$ | 6 | | | | | | | | | | |
| | B Bonzi | 2 | 0$^r$ | | | | | | | | E Ruusuvuori | 6 | 4 | 1 | | | | |
| | A Seppi | 6$^3$ | 6 | 1 | | | | | | 8 | I Ivashka | 4 | 6 | 6 | | | | |
| WC | T Skatov | 7$^7$ | 4 | 6 | WC | T Skatov | 2 | 3 | | | | | | | | | | |
| Q | E Ymer | 2 | 4 | | 8 | I Ivashka | 6 | 6 | | | | | | | | | | |
| 8 | I Ivashka | 6 | 6 | | | | | | | | | | | | 8 | I Ivashka | 3 | 6$^4$ |
| | | | | | | | | | | | | | | | | J Duckworth | 6 | 7$^7$ |
| | | | | | 4 | F Krajinović | 6$^2$ | 3 | | | | | | | | | | |
| WC | M Kukushkin | 6$^3$ | 1 | | | J Duckworth | 7$^7$ | 6 | | | | | | | | | | |
| | J Duckworth | 7$^7$ | 6 | | | | | | | | J Duckworth | 6 | 6 | | | | | |
| | J Veselý | 3 | 6$^6$ | | | | | | | 5 | J Millman | 4 | 4 | | | | | |
| | J Munar | 6 | 7$^8$ | | | J Munar | 4 | 7$^7$ | 5 | | | | | | | | | |
| Q | D Popko | 6 | 1 | 4 | 5 | J Millman | 6 | 6$^5$ | 7 | | | | | | | | | |
| 5 | J Millman | 3 | 6 | 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 | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 7 | L Đere | 6 | 3 | 6 | | | | | | | | | | | | | | | |
| | DE Galán | 4 | 6 | 4 | 7 | L Đere | 6 | 6$^3$ | 6 | | | | | | | | | | |
| Q | M Polmans | 4 | 6 | 4 | | L Musetti | 4 | 7$^7$ | 4 | | | | | | | | | | |
| | L Musetti | 6 | 2 | 6 | | | | | | 7 | L Đere | 6$^4$ | 6 | 0 | | | | | |
| | S-w Kwon | 6 | 6 | | | | | | | | S-w Kwon | 7$^7$ | 2 | 6 | | | | | |
| Q | E Donskoy | 4 | 3 | | | S-w Kwon | 7 | 6 | | | | | | | | | | | |
| | | | | | 3 | D Lajović | 5 | 4 | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | S-w Kwon | 3 | 7 | 6 |
| 6 | B Paire | 5 | 4 | | | | | | | | | | | | 2 | A Bublik | 6 | 5 | 3 |
| | E Gerasimov | 7 | 6 | | | E Gerasimov | 7 | 6$^5$ | 5 | | | | | | | | | | |
| | C Taberner | 7 | 6 | | | C Taberner | 5 | 7$^7$ | 7 | | | | | | | | | | |
| | R Berankis | 5 | 4 | | | | | | | | C Taberner | 3 | 4 | | | | | | |
| WC | F Verdasco | 4 | 2 | | | | | | | 2 | A Bublik | 6 | 6 | | | | | | |
| | M Kecmanović | 6 | 6 | | | M Kecmanović | 6 | 3 | 5 | | | | | | | | | | |
| | | | | | 2 | A Bublik | 2 | 6 | 7 | | | | | | | | | | |

## Qualifying
### Seeds

* Jurij Rodionov (first round)
* Maxime Cressy (qualifying competition)
* Marc Polmans (qualified)
* Evgeny Donskoy (qualified)
* Illya Marchenko (first round)
* Kacper Żuk (first round)
* Elias Ymer (qualified)
* Dmitry Popko (qualified)

### Qualifiers

* Dmitry Popko
* Elias Ymer
* Marc Polmans
* Evgeny Donskoy

### Qualifying draw
#### First qualifier

| First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 1 | Jurij Rodionov | 5 | 4 | | | | | |
| | Matthew Ebden | 7 | 6 | | | | | |
| | Matthew Ebden | 7 | 6 | | Matthew Ebden | 6 | 3 | 4 |
| | | | | 8 | Dmitry Popko | 3 | 6 | 6 |
| WC | Simon Anthony Ivanov | 2 | 3 | 8 | Dmitry Popko | 3 | 6 | 6 |
| 8 | Dmitry Popko | 6 | 6 | | | | | |

#### Second qualifier

| First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 2 | Maxime Cressy | 6 | 2 | | | | | |
| | Bernard Tomic | 3 | 1$^r$ | | | | | |
| | Bernard Tomic | 3 | 1$^r$ | 2 | Maxime Cressy | 3 | 6 | 4 |
| | | | | 7 | Elias Ymer | 6 | 4 | 6 |
| WC | Grigoriy Lomakin | 3 | 2 | 7 | Elias Ymer | 6 | 4 | 6 |
| 7 | Elias Ymer | 6 | 6 | | | | | |

#### Third qualifier

| First round | First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 3 | Marc Polmans | 2 | 7 | 4 | | | | |
| | Gian Marco Moroni | 6 | 5 | 1$^r$ | | | | |
| | Gian Marco Moroni | 6 | 5 | 1$^r$ | 3 | Marc Polmans | 6 | 6 |
| | | | | | Alt | Denis Yevseyev | 4 | 2 |
| Alt | Denis Yevseyev | 6 | 6 | | Alt | Denis Yevseyev | 4 | 2 |
| 5 | Illya Marchenko | 4 | 4 | | | | | |

#### Fourth qualifier

| First round | First round | First round | First round | Qualifying competition | Qualifying competition | Qualifying competition | Qualifying competition |
| 4 | Evgeny Donskoy | 7$^7$ | 6 | | | | |
| | Andrea Vavassori | 6$^4$ | 2 | | | | |
| | Andrea Vavassori | 6$^4$ | 2 | 4 | Evgeny Donskoy | 6 | 7$^7$ |
| | | | | | Pavel Kotov | 3 | 6$^4$ |
| | Pavel Kotov | 6 | 6 | | Pavel Kotov | 3 | 6$^4$ |
| 6 | Kacper Żuk | 2 | 3 | | | | |