# 2021 Columbus Challenger – Men's singles

J. J. Wolf was the defending champion but lost in the semifinals to Stefan Kozlov.
Kozlov won the title after defeating Max Purcell 4–6, 6–2, 6–4 in the final.

## Seeds

* Tennys Sandgren (quarterfinals)
* Salvatore Caruso (first round, retired)
* Alex Bolt (quarterfinals)
* Prajnesh Gunneswaran (second round)
* Jason Jung (first round)
* Ernesto Escobedo (first round)
* J. J. Wolf (semifinals)
* Mitchell Krueger (first 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 | Semifinals | Final | Final | Final | Final |
| 7 | J. J. Wolf | 6 | 3 | 5 | | | | |
| | Stefan Kozlov | 2 | 6 | 7 | | | | |
| | Stefan Kozlov | 2 | 6 | 7 | Stefan Kozlov | 4 | 6 | 6 |
| | | | | | Max Purcell | 6 | 2 | 4 |
| | Aleksandar Vukic | 6$^3$ | 6$^6$ | | Max Purcell | 6 | 2 | 4 |
| | Max Purcell | 7$^7$ | 7$^8$ | | | | | |

### 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 | Semifinals |
| 1 | T Sandgren | 6 | 6 | | | | | | | | | | | | | | | |
| LL | A Galarneau | 3 | 2 | | 1 | T Sandgren | 6 | 6 | | | | | | | | | | |
| Q | G Brouwer | 7$^7$ | 6 | | Q | G Brouwer | 4 | 4 | | | | | | | | | | |
| | D King | 6$^1$ | 0 | | | | | | 1 | T Sandgren | 3 | 6 | 6$^5$ | | | | | |
| | JC Aragone | 4 | 4 | | | | | | 7 | J. J. Wolf | 6 | 3 | 7$^7$ | | | | | |
| Q | E King | 6 | 6 | | Q | E King | 3 | 0 | | | | | | | | | | |
| | M Sasikumar | 3 | 2 | | 7 | J. J. Wolf | 6 | 6 | | | | | | | | | | |
| 7 | J. J. Wolf | 6 | 6 | | | | | | | | | | | 7 | J. J. Wolf | 6 | 3 | 5 |
| 4 | P Gunneswaran | 3 | 6 | 7 | | | | | | | | | | | S Kozlov | 2 | 6 | 7 |
| Q | A Kovacevic | 6 | 3 | 5 | 4 | P Gunneswaran | 1 | 4 | | | | | | | | | | |
| LL | S Mochizuki | 3 | 7$^7$ | 6$^5$ | | M Torpegaard | 6 | 6 | | | | | | | | | | |
| | M Torpegaard | 6 | 6$^3$ | 7$^7$ | | | | | | M Torpegaard | 6 | 6$^4$ | 4 | | | | | |
| | J Kubler | 7$^8$ | 6 | | | | | | | S Kozlov | 2 | 7$^7$ | 6 | | | | | |
| | P Polansky | 6$^6$ | 4 | | | J Kubler | 2 | 5 | | | | | | | | | | |
| | S Kozlov | 6 | 6 | | | S Kozlov | 6 | 7 | | | | | | | | | | |
| 8 | M Krueger | 0 | 3 | | | | | | | | | | | | | | | |

### 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 |
| 6 | E Escobedo | 4 | 5 | | | | | | | | | | | | | | |
| | A Vukic | 6 | 7 | | | A Vukic | 7$^7$ | 7 | | | | | | | | | |
| WC | Matěj Vocel | 7 | 1 | 6$^3$ | WC | C Kingsley | 6$^4$ | 5 | | | | | | | | | |
| WC | C Kingsley | 5 | 6 | 7$^7$ | | | | | | | A Vukic | 7 | 6 | | | | |
| Q | Y-s Chung | 6 | 4 | 6$^3$ | | | | | | 3 | A Bolt | 5 | 4 | | | | |
| | J-s Nam | 3 | 6 | 7$^7$ | | J-s Nam | 6$^5$ | 4 | | | | | | | | | |
| | N Rubin | 6$^5$ | 6$^4$ | | 3 | A Bolt | 7$^7$ | 6 | | | | | | | | | |
| 3 | A Bolt | 7$^7$ | 7$^7$ | | | | | | | | | | | | A Vukic | 6$^3$ | 6$^6$ |
| 5 | J Jung | 3 | 4 | | | | | | | | | | | | M Purcell | 7$^7$ | 7$^8$ |
| | R Peniston | 6 | 6 | | | R Peniston | 3 | 6$^7$ | | | | | | | | | |
| WC | J Tracy | 3 | 2 | | | M Purcell | 6 | 7$^9$ | | | | | | | | | |
| | M Purcell | 6 | 6 | | | | | | | | M Purcell | 6 | 3 | 6 | | | |
| Alt | N Chappell | 0$^r$ | | | | | | | | | N Mejía | 4 | 6 | 0 | | | |
| | N Mejía | 5 | | | | N Mejía | 6 | 0 | 6 | | | | | | | | |
| Alt | D Kelly | 6 | 3 | | Alt | D Kelly | 4 | 6 | 2 | | | | | | | | |
| 2 | S Caruso | 2 | 0$^r$ | | | | | | | | | | | | | | |