# 2021 Biella Challenger Indoor – Singles

This was the first of seven editions of the tournament in the 2021 tennis season.
Unseeded Illya Marchenko won the title after defeating the top seed Andy Murray 6–2, 6–4 in the final.

## Seeds

* Andy Murray (final)
* Federico Gaio (semifinals)
* Mohamed Safwat (second round)
* Lorenzo Giustino (quarterfinals)
* Martin Kližan (first round)
* Blaž Rola (quarterfinals)
* Filip Horanský (second round)
* Dmitry Popko (second 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 | Final | Final | Final | Final |
| 1/WC | Andy Murray | 6 | 7 | | | | |
| | Mathias Bourgue | 0 | 5 | | | | |
| | Mathias Bourgue | 0 | 5 | 1/WC | Andy Murray | 2 | 4 |
| | | | | | Illya Marchenko | 6 | 6 |
| | Illya Marchenko | 7 | 6 | | Illya Marchenko | 6 | 6 |
| 2 | Federico Gaio | 5 | 1 | | | | |

### 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/WC | A Murray | 6$^3$ | 6 | 6 | | | | | | | | | | | | | | |
| | M Marterer | 7$^7$ | 2 | 3 | 1/WC | A Murray | 6 | 6 | | | | | | | | | | |
| | E Karlovskiy | 6$^4$ | 4 | | | GM Moroni | 4 | 4 | | | | | | | | | | |
| | GM Moroni | 7$^7$ | 6 | | | | | | | 1/WC | A Murray | 6 | 7$^{11}$ | | | | | |
| | B Kavčič | 3 | 6 | 5 | | | | | | 6 | B Rola | 4 | 6$^9$ | | | | | |
| | M Viola | 6 | 3 | 7 | | M Viola | 6 | 5 | 4 | | | | | | | | | |
| | T-S Kwiatkowski | 3 | 2 | | 6 | B Rola | 3 | 7 | 6 | | | | | | | | | |
| 6 | B Rola | 6 | 6 | | | | | | | | | | | | 1/WC | A Murray | 6 | 7 |
| 3 | M Safwat | 4 | 6 | 6 | | | | | | | | | | | | M Bourgue | 0 | 5 |
| | H Moriya | 6 | 3 | 2 | 3 | M Safwat | 6 | 2 | 3 | | | | | | | | | |
| WC | A Andreev | 2 | 5 | | | M Bachinger | 4 | 6 | 6 | | | | | | | | | |
| | M Bachinger | 6 | 7 | | | | | | | | M Bachinger | 1 | 7$^7$ | 1 | | | | |
| | M Bourgue | 7$^7$ | 6 | | | | | | | | M Bourgue | 6 | 6$^3$ | 6 | | | | |
| | A Pellegrino | 6$^4$ | 1 | | | M Bourgue | 6 | 7 | | | | | | | | | | |
| Q | Fabrizio Ornago | 2 | 2 | | 7 | F Horanský | 3 | 5 | | | | | | | | | | |
| 7 | F Horanský | 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 |
| 5 | M Kližan | 2 | 6$^7$ | | | | | | | | | | | | | | | |
| | I Marchenko | 6 | 7$^9$ | | | I Marchenko | 7$^{10}$ | 6 | | | | | | | | | | |
| | T Fabbiano | 1 | 4 | | WC | L Vanni | 6$^8$ | 1 | | | | | | | | | | |
| WC | L Vanni | 6 | 6 | | | | | | | | I Marchenko | 6 | 2 | 7 | | | | |
| | T Kamke | 3 | 5 | | | | | | | 4 | L Giustino | 2 | 6 | 5 | | | | |
| | R Marcora | 6 | 7 | | | R Marcora | 6$^3$ | 5 | | | | | | | | | | |
| Q | J Sels | 4 | 3 | | 4 | L Giustino | 7$^7$ | 7 | | | | | | | | | | |
| 4 | L Giustino | 6 | 6 | | | | | | | | | | | | | I Marchenko | 7 | 6 |
| 8 | D Popko | 6 | 6 | | | | | | | | | | | | 2 | F Gaio | 5 | 1 |
| | M Jaziri | 1 | 3 | | 8 | D Popko | 6 | 2 | 3 | | | | | | | | | |
| | D Masur | 6 | 7 | | | D Masur | 4 | 6 | 6 | | | | | | | | | |
| | S Napolitano | 3 | 5 | | | | | | | | D Masur | 3 | 3 | | | | | |
| Q | T van Rijthoven | 6 | 3 | 6 | | | | | | 2 | F Gaio | 6 | 6 | | | | | |
| Q | G Fonio | 4 | 6 | 3 | Q | T van Rijthoven | 4 | 4 | | | | | | | | | | |
| | L Lacko | 3 | 4 | | 2 | F Gaio | 6 | 6 | | | | | | | | | | |
| 2 | F Gaio | 6 | 6 | | | | | | | | | | | | | | | |