# 2023 Nonthaburi Challenger III – Singles

Arthur Cazaux was the defending champion but lost in the final to Sho Shimabukuro.
Shimabukuro won the title after defeating Cazaux 6–2, 7–5 in the final.

## Seeds

* James Duckworth (second round)
* Alexander Ritschard (first round)
* Antoine Escoffier (quarterfinals, retired)
* Evan Furness (first round)
* Paul Jubb (first round)
* Nicholas David Ionel (first round)
* Peter Gojowczyk (withdrew)
* Zdeněk Kolář (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 | Final | Final | Final | Final |
| | Sho Shimabukuro | 6 | 7 | | | | |
| | Hong Seong-chan | 2 | 5 | | | | |
| | Hong Seong-chan | 2 | 5 | | Sho Shimabukuro | 6 | 7 |
| | | | | Q | Arthur Cazaux | 2 | 5 |
| LL | Giovanni Fonio | 5 | 3 | Q | Arthur Cazaux | 2 | 5 |
| Q | Arthur Cazaux | 7 | 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 | Quarterfinals | Semifinals | Semifinals | Semifinals |
| 1 | J Duckworth | 6 | 6 | | | | | | | | | | | | | | |
| Alt | B Zhukayev | 3 | 4 | | 1 | J Duckworth | 6$^4$ | 6 | 1 | | | | | | | | |
| | S Shimabukuro | 6 | 6 | | | S Shimabukuro | 7$^7$ | 4 | 6 | | | | | | | | |
| | M Moraing | 3 | 2 | | | | | | | | S Shimabukuro | 6 | 6$^7$ | 6 | | | |
| | J Choinski | 6 | 6 | | | | | | | 8 | Z Kolář | 0 | 7$^9$ | 2 | | | |
| WC | J Navasirisomboon | 1 | 3 | | | J Choinski | 4 | 6 | 0 | | | | | | | | |
| Q | E Donskoy | 6 | 6$^7$ | 2 | 8 | Z Kolář | 6 | 3 | 6 | | | | | | | | |
| 8 | Z Kolář | 3 | 7$^9$ | 6 | | | | | | | | | | | S Shimabukuro | 6 | 7 |
| 4 | E Furness | 1 | 1 | | | | | | | | | | | | S-c Hong | 2 | 5 |
| | K Żuk | 6 | 6 | | | K Żuk | 3 | 4 | | | | | | | | | |
| WC | Y Charoenphon | 3 | 1 | | | M Geerts | 6 | 6 | | | | | | | | | |
| | M Geerts | 6 | 6 | | | | | | | | M Geerts | 1 | 5 | | | | |
| | S-c Hong | 6 | 6 | | | | | | | | S-c Hong | 6 | 7 | | | | |
| WC | K Samrej | 4 | 4 | | | S-c Hong | 6 | 7$^7$ | | | | | | | | | |
| | NH Lý | 6 | 7$^7$ | | | NH Lý | 2 | 6$^3$ | | | | | | | | | |
| 6 | ND Ionel | 1 | 6$^5$ | | | | | | | | | | | | | | |

### 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 |
| LL | G Fonio | 6 | 7 | | | | | | | | | | | | | | | |
| | D Yevseyev | 2 | 5 | | LL | G Fonio | 6$^4$ | 6 | 6 | | | | | | | | | |
| | H Moriya | 0 | 4 | | | B Hassan | 7$^7$ | 4 | 2 | | | | | | | | | |
| | B Hassan | 6 | 6 | | | | | | | LL | G Fonio | 7 | 6$^5$ | 2 | | | | |
| | D Michalski | 6 | 6 | | | | | | | 3 | A Escoffier | 5 | 7$^7$ | 1$^r$ | | | | |
| Q | Dominik Palán | 4 | 2 | | | D Michalski | 3 | 6 | 1 | | | | | | | | | |
| Alt | S Travaglia | 1 | 6$^4$ | | 3 | A Escoffier | 6 | 4 | 6 | | | | | | | | | |
| 3 | A Escoffier | 6 | 7$^7$ | | | | | | | | | | | | LL | G Fonio | 5 | 3 |
| 5 | P Jubb | 6 | 4 | 5 | | | | | | | | | | | Q | A Cazaux | 7 | 6 |
| Q | S Mochizuki | 2 | 6 | 7 | Q | S Mochizuki | 3 | 1 | | | | | | | | | | |
| | D Added | 6 | 4 | 1 | | T Sandgren | 6 | 6 | | | | | | | | | | |
| | T Sandgren | 1 | 6 | 6 | | | | | | | T Sandgren | 6$^4$ | 4 | | | | | |
| Q | A Cazaux | 7$^7$ | 6 | | | | | | | Q | A Cazaux | 7$^7$ | 6 | | | | | |
| Q | S Parker | 6$^1$ | 4 | | Q | A Cazaux | 6 | 6 | | | | | | | | | | |
| Q | J Menšík | 7$^7$ | 7 | | Q | J Menšík | 3 | 0 | | | | | | | | | | |
| 2 | A Ritschard | 6$^5$ | 5 | | | | | | | | | | | | | | | |