# 2021 Moneta Czech Open – Singles

Kamil Majchrzak was the defending champion but chose not to defend his title.
Federico Coria won the title after defeating Alex Molčan 7–6$^{(7–1)}$, 6–3 in the final.

## Seeds

* Pablo Andújar (first round)
* Jiří Veselý (second round)
* Gianluca Mager (semifinals)
* Federico Coria (champion)
* Hugo Dellien (quarterfinals)
* Jozef Kovalík (first round)
* Juan Manuel Cerúndolo (first round, retired)
* Blaž Rola (quarterfinals)

## 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 |
| | Alex Molčan | 6 | 6 | | | | |
| 3 | Gianluca Mager | 1 | 3 | | | | |
| 3 | Gianluca Mager | 1 | 3 | | Alex Molčan | 6$^1$ | 3 |
| | | | | 4 | Federico Coria | 7$^7$ | 6 |
| 4 | Federico Coria | 6 | 6 | 4 | Federico Coria | 7$^7$ | 6 |
| | Zdeněk Kolář | 4 | 2 | | | | |

### 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 | P Andújar | 6 | 1 | 4 | | | | | | | | | | | | |
| | Yo Watanuki | 1 | 6 | 6 | | Yo Watanuki | 1 | 2 | | | | | | | | |
| | A Molčan | 6 | 6 | | | A Molčan | 6 | 6 | | | | | | | | |
| Q | David Poljak | 3 | 3 | | | | | | | A Molčan | 6 | 6 | | | | |
| | G Oliveira | 3 | 6 | 4 | | | | | 5 | H Dellien | 3 | 1 | | | | |
| | M Vrbenský | 6 | 2 | 6 | | M Vrbenský | 1 | 2 | | | | | | | | |
| WC | A Paulson | 1 | 3 | | 5 | H Dellien | 6 | 6 | | | | | | | | |
| 5 | H Dellien | 6 | 6 | | | | | | | | | | | A Molčan | 6 | 6 |
| 3 | G Mager | 6 | 6 | | | | | | | | | | 3 | G Mager | 1 | 3 |
| Alt | J Forejtek | 3 | 3 | | 3 | G Mager | 7$^{10}$ | 6 | | | | | | | | |
| WC | Daniel Siniakov | 1 | 0 | | | S Báez | 6$^8$ | 2 | | | | | | | | |
| | S Báez | 6 | 6 | | | | | | 3 | G Mager | 6 | 6 | | | | |
| | M Bachinger | 6 | 0 | 1 | | | | | WC | D Svrčina | 3 | 2 | | | | |
| WC | D Svrčina | 2 | 6 | 6 | WC | D Svrčina | 6 | 7 | | | | | | | | |
| Q | A Erler | 7$^7$ | 4 | | Q | A Erler | 1 | 5 | | | | | | | | |
| 7 | JM Cerúndolo | 6$^1$ | 2$^r$ | | | | | | | | | | | | | |

### 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 | Semifinals |
| 8 | B Rola | 6 | 7 | | | | | | | | | | | | | | |
| Q | A Rybakov | 1 | 5 | | 8 | B Rola | 6 | 3 | 7$^8$ | | | | | | | | |
| | J Lehečka | 5 | 5 | | | L Klein | 4 | 6 | 6$^6$ | | | | | | | | |
| | L Klein | 7 | 7 | | | | | | | 8 | B Rola | 4 | 1 | | | | |
| PR | A Kuznetsov | 6 | 7$^7$ | | | | | | | 4 | F Coria | 6 | 6 | | | | |
| LL | J Sels | 0 | 6$^4$ | | PR | A Kuznetsov | 7$^7$ | 5 | 2 | | | | | | | | |
| LL | J Härteis | 1 | 0 | | 4 | F Coria | 6$^0$ | 7 | 6 | | | | | | | | |
| 4 | F Coria | 6 | 6 | | | | | | | | | | | 4 | F Coria | 6 | 6 |
| 6 | J Kovalík | 6 | 6$^4$ | 4 | | | | | | | | | | | Z Kolář | 4 | 2 |
| | V Kopřiva | 2 | 7$^7$ | 6 | | V Kopřiva | 3 | 6$^3$ | | | | | | | | | |
| | L Miedler | 2 | 2 | | | Z Kolář | 6 | 7$^7$ | | | | | | | | | |
| | Z Kolář | 6 | 6 | | | | | | | | Z Kolář | 6 | 6 | | | | |
| Q | S Mansouri | 0 | 6 | 2 | | | | | | | T Kamke | 2 | 3 | | | | |
| | T Kamke | 6 | 3 | 6 | | T Kamke | 6 | 6 | | | | | | | | | |
| | F Mena | 2 | 6$^5$ | | 2 | J Veselý | 3 | 4 | | | | | | | | | |
| 2 | J Veselý | 6 | 7$^7$ | | | | | | | | | | | | | | |