# 2021 Amex-Istanbul Challenger II – Singles

Arthur Rinderknech was the defending champion but chose not to defend his title.
James Duckworth won the title after defeating Wu Tung-lin 6–4, 6–2 in the final.

## Seeds

* James Duckworth (champion)
* Radu Albot (second round)
* Daniel Elahi Galán (first round)
* Yasutaka Uchiyama (quarterfinals)
* Marc Polmans (second round)
* Evgeny Donskoy (second round)
* Illya Marchenko (second round)
* Mohamed Safwat (withdrew)

## 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 | James Duckworth | 6$^9$ | 6 | 6 | | | | |
| | Quentin Halys | 7$^{11}$ | 3 | 4 | | | | |
| | Quentin Halys | 7$^{11}$ | 3 | 4 | 1 | James Duckworth | 6 | 6 |
| | | | | | | Wu Tung-lin | 4 | 2 |
| | Borna Gojo | 4 | 6 | 4 | | Wu Tung-lin | 4 | 2 |
| | Wu Tung-lin | 6 | 3 | 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 | J Duckworth | 7 | 6 | | | | | | | | | | | | | | | |
| | L Giustino | 5 | 1 | | 1 | J Duckworth | 6 | 6 | | | | | | | | | | |
| | A Müller | 6 | 6 | | | A Müller | 3 | 2 | | | | | | | | | | |
| Q | N Chappell | 4 | 2 | | | | | | | 1 | J Duckworth | 6 | 6 | | | | | |
| WC | S Ağabigün | 4 | 6 | 4 | | | | | | | H Grenier | 3 | 3 | | | | | |
| | H Grenier | 6 | 3 | 6 | | H Grenier | 6 | 6 | | | | | | | | | | |
| | A Kuznetsov | 6$^4$ | 1 | | 6 | E Donskoy | 4 | 4 | | | | | | | | | | |
| 6 | E Donskoy | 7$^7$ | 6 | | | | | | | | | | | 1 | J Duckworth | 6$^9$ | 6 | 6 |
| 4 | Y Uchiyama | 6 | 3 | 6 | | | | | | | | | | | Q Halys | 7$^{11}$ | 3 | 4 |
| | H Moriya | 3 | 6 | 3 | 4 | Y Uchiyama | 3 | 6 | 6 | | | | | | | | | |
| Q | Christopher Heyman | 3 | 6 | 6 | Q | C Heyman | 6 | 3 | 4 | | | | | | | | | |
| | A Arnaboldi | 6 | 2 | 4 | | | | | | 4 | Y Uchiyama | 5 | 2 | | | | | |
| | B Tomic | 0 | 1 | | | | | | | | Q Halys | 7 | 6 | | | | | |
| | Q Halys | 6 | 6 | | | Q Halys | 3 | 6 | 6 | | | | | | | | | |
| | T Fabbiano | 5 | 2 | | 7 | I Marchenko | 6 | 2 | 2 | | | | | | | | | |
| 7 | I Marchenko | 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 | Semifinals | Semifinals | Semifinals | Semifinals |
| LL | G Blancaneaux | 4 | 7$^7$ | 6 | | | | | | | | | | | | | |
| Q | L Lokoli | 6 | 6$^5$ | 1 | LL | G Blancaneaux | 6 | 7 | | | | | | | | | |
| | C-h Tseng | 6 | 2 | 6 | | C-h Tseng | 3 | 5 | | | | | | | | | |
| | R Marcora | 1 | 6 | 4 | | | | | | LL | G Blancaneaux | 6$^6$ | 4 | | | | |
| | E Tiurnev | 5 | 6 | 0 | | | | | | | B Gojo | 7$^8$ | 6 | | | | |
| | E Karlovskiy | 7 | 4 | 6 | | E Karlovskiy | 1 | 7$^7$ | 6$^5$ | | | | | | | | |
| | B Gojo | 6 | 3 | 6 | | B Gojo | 6 | 6$^4$ | 7$^7$ | | | | | | | | |
| 3 | DE Galán | 4 | 6 | 2 | | | | | | | | | | B Gojo | 4 | 6 | 4 |
| 5 | M Polmans | 6 | 6 | | | | | | | | | | | T-l Wu | 6 | 3 | 6 |
| WC | K Kırcı | 3 | 2 | | 5 | M Polmans | 2 | 6 | 1 | | | | | | | | |
| | T Ito | 3 | 2 | | | T-l Wu | 6 | 3 | 6 | | | | | | | | |
| | T-l Wu | 6 | 6 | | | | | | | | T-l Wu | 6 | 6 | | | | |
| Q | A Šetkić | 6 | 6 | | | | | | | Q | A Šetkić | 3 | 2 | | | | |
| WC | VV Cornea | 4 | 2 | | Q | A Šetkić | 4 | 6 | 7 | | | | | | | | |
| | M Ebden | 4 | 6 | 1 | 2 | R Albot | 6 | 3 | 5 | | | | | | | | |
| 2 | R Albot | 6 | 1 | 6 | | | | | | | | | | | | | |