# 2021 Koser Jewelers Tennis Challenge – Singles

Madison Brengle was the defending champion, having won the previous edition in 2019, but lost in the second round to Lesley Pattinama Kerkhove.
Nuria Párrizas Díaz won the title, defeating Greet Minnen in the final, 7–6$^{(8–6)}$, 4–6, 7–6$^{(9–7)}$.

## Seeds

* Madison Brengle (second round)
* Clara Tauson (second round, retired)
* Nuria Párrizas Díaz (champion)
* Greet Minnen (final)
* Varvara Lepchenko (withdrew)
* Ysaline Bonaventure (first round)
* Anna Kalinskaya (first round)
* Caty McNally (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 | Semifinals | Final | Final | Final | Final | Final |
| | Lesley Pattinama Kerkhove | 3 | 1 | | | | | | |
| 4 | Greet Minnen | 6 | 6 | | | | | | |
| 4 | Greet Minnen | 6 | 6 | | 4 | Greet Minnen | 6$^6$ | 6 | 6$^7$ |
| | | | | | 3 | Nuria Párrizas Díaz | 7$^8$ | 4 | 7$^9$ |
| 3 | Nuria Párrizas Díaz | 2 | 6 | 6 | 3 | Nuria Párrizas Díaz | 7$^8$ | 4 | 7$^9$ |
| | Katarzyna Kawa | 6 | 0 | 3 | | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | M Brengle | 6 | 7 | | | | | | | | | | | | | | |
| WC | A Glatch | 1 | 5 | | 1 | M Brengle | 3 | 6$^4$ | | | | | | | | | |
| | L Cabrera | 2 | 3 | | | L Pattinama Kerkhove | 6 | 7$^7$ | | | | | | | | | |
| | L Pattinama Kerkhove | 6 | 6 | | | | | | | L Pattinama Kerkhove | 6$^2$ | 6 | 6 | | | | |
| Q | D Snigur | 0$^r$ | | | | | | | Q | B Haddad Maia | 7$^7$ | 4 | 1 | | | | |
| Q | B Haddad Maia | 5 | | | Q | B Haddad Maia | 6 | 6 | | | | | | | | | |
| LL | S Chang | 7$^7$ | 7 | | LL | S Chang | 4 | 4 | | | | | | | | | |
| 7 | A Kalinskaya | 6$^5$ | 5 | | | | | | | | | | | | L Pattinama Kerkhove | 3 | 1 |
| 4 | G Minnen | 6$^6$ | 6 | 6 | | | | | | | | | | 4 | G Minnen | 6 | 6 |
| | F Di Lorenzo | 7$^8$ | 2 | 2 | 4 | G Minnen | 6 | 6 | | | | | | | | | |
| Q | M Hontama | 6 | 4 | | Q | M Hontama | 3 | 2 | | | | | | | | | |
| WC | D Lao | 2 | 1$^r$ | | | | | | 4 | G Minnen | 7 | 6 | | | | | |
| | C Dolehide | 4 | 4 | | | | | | 8 | C McNally | 5 | 3 | | | | | |
| Q | M Hibi | 6 | 6 | | Q | M Hibi | 4 | 6$^2$ | | | | | | | | | |
| Q | A Sutjiadi | 5 | 4 | | 8 | C McNally | 6 | 7$^7$ | | | | | | | | | |
| 8 | C McNally | 7 | 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 |
| 6 | Y Bonaventure | 6$^4$ | 2 | | | | | | | | | | | | | | | | |
| Q | E Raducanu | 7$^7$ | 6 | | Q | E Raducanu | 3 | 6 | 6 | | | | | | | | | | |
| Q | E Gorgodze | 6$^3$ | 6 | 1 | | E Gorgodze | 6 | 0 | 1 | | | | | | | | | | |
| | C Vandeweghe | 7$^7$ | 3 | 0$^r$ | | | | | | Q | E Raducanu | 3$^r$ | | | | | | | |
| WC | G Min | 6 | 5 | 7$^7$ | | | | | | 3 | N Párrizas Díaz | 4 | | | | | | | |
| PR | V Diatchenko | 3 | 7 | 6$^4$ | WC | G Min | 2 | 6 | 1 | | | | | | | | | | |
| WC | J Loeb | 6$^2$ | 2 | | 3 | N Párrizas Díaz | 6 | 3 | 6 | | | | | | | | | | |
| 3 | N Párrizas Díaz | 7$^7$ | 6 | | | | | | | | | | | | 3 | N Párrizas Díaz | 2 | 6 | 6 |
| Q | A Raina | 6 | 6 | | | | | | | | | | | | | K Kawa | 6 | 0 | 3 |
| | R Zarazúa | 3 | 2 | | Q | A Raina | 3 | 7$^7$ | 4 | | | | | | | | | | |
| | K Kawa | 3 | 6 | 7 | | K Kawa | 6 | 6$^4$ | 6 | | | | | | | | | | |
| | L Küng | 6 | 1 | 5 | | | | | | | K Kawa | 6 | 2 | 6 | | | | | |
| | M Fręch | 6 | 6 | | | | | | | | M Fręch | 4 | 6 | 2 | | | | | |
| | C Bucșa | 2 | 3 | | | M Fręch | 7$^{10}$ | 0 | | | | | | | | | | | |
| | Ar Rodionova | 1 | 2 | | 2 | C Tauson | 6$^8$ | 0$^r$ | | | | | | | | | | | |
| 2 | C Tauson | 6 | 6 | | | | | | | | | | | | | | | | |