# 2023 Nonthaburi Challenger II – Singles

Dennis Novak was the defending champion but lost in the semifinals to Arthur Cazaux.
Cazaux won the title after defeating Lloyd Harris 7–6$^{(7–5)}$, 6–2 in the final.

## Seeds

* Dennis Novak (semifinals)
* Lloyd Harris (final)
* Kacper Żuk (first round)
* Zdeněk Kolář (first round)
* Michael Geerts (second round)
* Daniel Michalski (quarterfinals)
* Sho Shimabukuro (first round)
* Tennys Sandgren (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 |
| 1 | Dennis Novak | 4 | 6 | 2 | | | | |
| Q | Arthur Cazaux | 6 | 4 | 6 | | | | |
| Q | Arthur Cazaux | 6 | 4 | 6 | Q | Arthur Cazaux | 7$^7$ | 6 |
| | | | | | 2 | Lloyd Harris | 6$^5$ | 2 |
| Q | Jason Jung | 1 | 4 | | 2 | Lloyd Harris | 6$^5$ | 2 |
| 2 | Lloyd Harris | 6 | 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 | D Novak | 6 | 7$^9$ | | | | | | | | | | | | | | | |
| Q | H Squire | 3 | 6$^7$ | | 1 | D Novak | 6 | 6 | | | | | | | | | | |
| | V Royer | 6 | 0 | | | V Royer | 2 | 3 | | | | | | | | | | |
| Alt | B Harris | 1 | 0$^r$ | | | | | | | 1 | D Novak | 6 | 6 | | | | | |
| | M Gengel | 6 | 6 | | | | | | | | M Gengel | 3 | 3 | | | | | |
| | H Moriya | 1 | 2 | | | M Gengel | 2 | 7$^7$ | 7 | | | | | | | | | |
| WC | P Kovapitukted | 1 | 3 | | 5 | M Geerts | 6 | 6$^0$ | 5 | | | | | | | | | |
| 5 | M Geerts | 6 | 6 | | | | | | | | | | | 1 | D Novak | 4 | 6 | 2 |
| 4 | Z Kolář | 3 | 3 | | | | | | | | | | | Q | A Cazaux | 6 | 4 | 6 |
| Alt | P Gunneswaran | 6 | 6 | | Alt | P Gunneswaran | 7$^7$ | 6$^4$ | 3 | | | | | | | | | |
| Q | G Fonio | 4 | 4 | | Q | A Cazaux | 6$^5$ | 7$^7$ | 6 | | | | | | | | | |
| Q | A Cazaux | 6 | 6 | | | | | | | Q | A Cazaux | 6 | 6 | | | | | |
| | B Hassan | 7 | 7 | | | | | | | 8 | T Sandgren | 3 | 3 | | | | | |
| Q | Alafia Ayeni | 5 | 5 | | | B Hassan | 3 | 6 | 6$^6$ | | | | | | | | | |
| | D Added | 6 | 6$^2$ | 4 | 8 | T Sandgren | 6 | 1 | 7$^8$ | | | | | | | | | |
| 8 | T Sandgren | 2 | 7$^7$ | 6 | | | | | | | | | | | | | | |

### Bottom 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 |
| 7 | S Shimabukuro | 4 | 1 | | | | | | | | | | | | | | |
| Q | J Jung | 6 | 6 | | Q | J Jung | 6 | 7$^7$ | | | | | | | | | |
| | B Zhukayev | 7$^7$ | 7$^7$ | | | B Zhukayev | 4 | 6$^3$ | | | | | | | | | |
| WC | W Trongcharoenchaikul | 6$^2$ | 6$^5$ | | | | | | Q | J Jung | 4 | 7 | 6 | | | | |
| | D Yevseyev | 4 | 6$^1$ | | | | | | Q | E Donskoy | 6 | 5 | 3 | | | | |
| Q | E Donskoy | 6 | 7$^7$ | | Q | E Donskoy | 6 | 7$^7$ | | | | | | | | | |
| | Y Uchiyama | 6 | 6 | | | Y Uchiyama | 4 | 6$^3$ | | | | | | | | | |
| 3 | K Żuk | 2 | 1 | | | | | | | | | | | Q | J Jung | 1 | 4 |
| 6 | D Michalski | 3 | 7 | 6 | | | | | | | | | | 2 | L Harris | 6 | 6 |
| | S Mochizuki | 6 | 5 | 3 | 6 | D Michalski | 7$^7$ | 7$^{10}$ | | | | | | | | | |
| | S Travaglia | 6$^5$ | 7 | 6 | | S Travaglia | 6$^4$ | 6$^8$ | | | | | | | | | |
| | A Arnaboldi | 7$^7$ | 5 | 3 | | | | | 6 | D Michalski | 4 | 3 | | | | | |
| | M Sasikumar | 4 | 4 | | | | | | 2 | L Harris | 6 | 6 | | | | | |
| | M Moraing | 6 | 6 | | | M Moraing | 1 | 3 | | | | | | | | | |
| WC | K Samrej | 1 | 2 | | 2 | L Harris | 6 | 6 | | | | | | | | | |
| 2 | L Harris | 6 | 6 | | | | | | | | | | | | | | |