# 2017 Seoul Open Challenger – Singles

Sergiy Stakhovsky was the defending champion but chose not to defend his title.
Thomas Fabbiano won the title after defeating Kwon Soon-woo 1–6, 6–4, 6–3 in the final.

## Seeds

* Lu Yen-hsun (first round)
* Chung Hyeon (withdrew)
* Dudi Sela (quarterfinals, retired)
* Konstantin Kravchuk (first round)
* Vasek Pospisil (second round)
* Blaž Kavčič (first round)
* Illya Marchenko (first round)
* Ruben Bemelmans (semifinals)

## 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 |
| 8 | Ruben Bemelmans | 4 | 1 | | | | |
| | Thomas Fabbiano | 6 | 6 | | | | |
| | Thomas Fabbiano | 6 | 6 | Thomas Fabbiano | 1 | 6 | 6 |
| | | | | Kwon Soon-woo | 6 | 4 | 3 |
| | Lee Duck-hee | 3 | 0 | Kwon Soon-woo | 6 | 4 | 3 |
| | Kwon Soon-woo | 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 | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | Y-h Lu | 3 | 4 | | | | | | | | | | | | | | | |
| WC | Y-s Chung | 6 | 6 | | WC | Y-s Chung | 6 | 6$^4$ | 3 | | | | | | | | | |
| SE | L Broady | 3 | 4 | | | H Moriya | 4 | 7$^7$ | 6 | | | | | | | | | |
| | H Moriya | 6 | 6 | | | | | | | | H Moriya | 3 | 1 | | | | | |
| | A Santillan | 7 | 4 | 3 | | | | | | 8 | R Bemelmans | 6 | 6 | | | | | |
| LL | L Saville | 5 | 6 | 6 | LL | L Saville | 4 | 6 | 5 | | | | | | | | | |
| | B Klein | 4 | 6 | 1 | 8 | R Bemelmans | 6 | 3 | 7 | | | | | | | | | |
| 8 | R Bemelmans | 6 | 3 | 6 | | | | | | | | | | | 8 | R Bemelmans | 4 | 1 |
| 4 | K Kravchuk | 4 | 3 | | | | | | | | | | | | | T Fabbiano | 6 | 6 |
| | G Soeda | 6 | 6 | | | G Soeda | 6 | 6 | | | | | | | | | | |
| PR | A Ward | 3 | 4 | | WC | Y-s Kim | 2 | 4 | | | | | | | | | | |
| WC | Kim Young-seok | 6 | 6 | | | | | | | | G Soeda | 6 | 2 | 3 | | | | |
| | O Jasika | 4 | 7$^8$ | 6$^1$ | | | | | | | T Fabbiano | 3 | 6 | 6 | | | | |
| | M Chiudinelli | 6 | 6$^6$ | 7$^7$ | | M Chiudinelli | 1 | 2 | | | | | | | | | | |
| | T Fabbiano | 6 | 6 | | | T Fabbiano | 6 | 6 | | | | | | | | | | |
| 7 | I Marchenko | 2 | 4 | | | | | | | | | | | | | | | |

### Bottom half

| 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 |
| 5 | V Pospisil | 6 | 6 | | | | | | | | | | | | | |
| | S Doumbia | 3 | 2 | 5 | V Pospisil | 6 | 6$^3$ | 6$^6$ | | | | | | | | |
| | D-h Lee | 6 | 6 | | D-h Lee | 2 | 7$^7$ | 7$^8$ | | | | | | | | |
| Q | Shuichi Sekiguchi | 0 | 3 | | | | | | | D-h Lee | 5 | 7$^9$ | 3 | | | |
| | S Bangoura | 2 | 1 | | | | | | 3 | D Sela | 7 | 6$^7$ | 0$^r$ | | | |
| Q | F Auger-Aliassime | 6 | 6 | Q | F Auger-Aliassime | 3 | 1 | | | | | | | | | |
| WC | Ho Chung | 5 | 3 | 3 | D Sela | 6 | 6 | | | | | | | | | |
| 3 | D Sela | 7 | 6 | | | | | | | | | | | D-h Lee | 3 | 0 |
| 6 | B Kavčič | 6$^4$ | 3 | | | | | | | | | | | S-w Kwon | 6 | 6 |
| | S-w Kwon | 7$^7$ | 6 | | S-w Kwon | 7$^7$ | 6 | | | | | | | | | |
| | T Ito | 2 | 3 | Alt | M Tepavac | 6$^1$ | 1 | | | | | | | | | |
| Alt | M Tepavac | 6 | 6 | | | | | | | S-w Kwon | 6$^7$ | 6 | 6 | | | |
| Q | A Krajicek | 7$^{16}$ | 6 | | | | | | | A Sarkissian | 7$^9$ | 4 | 3 | | | |
| WC | S-c Hong | 6$^{14}$ | 3 | Q | A Krajicek | 1 | 2 | | | | | | | | | |
| | A Sarkissian | 6 | 6 | | A Sarkissian | 6 | 6 | | | | | | | | | |
| Q | D Nguyen | 3 | 4 | | | | | | | | | | | | | |