# 2018 Oracle Challenger Series – Chicago – Men's singles

This was the first edition of the tournament.
Denis Istomin won the title after defeating Reilly Opelka 6–4, 6–2 in the final.

## Seeds

* Andreas Seppi (first round)
* Denis Istomin (champion)
* Vasek Pospisil (first round)
* Viktor Troicki (first round)
* Michael Mmoh (second round)
* Ruben Bemelmans (quarterfinals)
* Elias Ymer (first round)
* Noah Rubin (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 |
| Alt | Dominik Köpfer | 3 | 6$^3$ | | | | |
| | Reilly Opelka | 6 | 7$^7$ | | | | |
| | Reilly Opelka | 6 | 7$^7$ | | Reilly Opelka | 4 | 2 |
| | | | | 2 | Denis Istomin | 6 | 6 |
| | Bjorn Fratangelo | 1 | 2 | 2 | Denis Istomin | 6 | 6 |
| 2 | Denis Istomin | 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/WC | A Seppi | 3 | 6$^5$ | | | | | | | | | | | | | | | |
| Q | A Sarkissian | 6 | 7$^7$ | | Q | A Sarkissian | 6 | 6$^4$ | 6$^3$ | | | | | | | | | |
| | DE Galán | 6$^5$ | 3 | | | JC Aragone | 2 | 7$^7$ | 7$^7$ | | | | | | | | | |
| | JC Aragone | 7$^7$ | 6 | | | | | | | | JC Aragone | 4 | 2 | | | | | |
| Alt | D Köpfer | 6 | 6 | | | | | | | Alt | D Köpfer | 6 | 6 | | | | | |
| Q | V Millot | 3 | 4 | | Alt | D Köpfer | 4 | 7$^7$ | 6 | | | | | | | | | |
| | M Krueger | 3 | 6 | 6 | | M Krueger | 6 | 6$^4$ | 2 | | | | | | | | | |
| 7 | E Ymer | 6 | 3 | 2 | | | | | | | | | | | Alt | D Köpfer | 3 | 6$^3$ |
| 3 | V Pospisil | 2 | 2 | | | | | | | | | | | | | R Opelka | 6 | 7$^7$ |
| Alt | D Young | 6 | 6 | | Alt | D Young | 6 | 6 | | | | | | | | | | |
| | J-P Smith | 2 | 6 | 6 | | J-P Smith | 3 | 4 | | | | | | | | | | |
| Alt | R Cid Subervi | 6 | 1 | 4 | | | | | | Alt | D Young | 6 | 2 | 6$^5$ | | | | |
| | R Quiroz | 3 | 2 | | | | | | | | R Opelka | 3 | 6 | 7$^7$ | | | | |
| | R Opelka | 6 | 6 | | | R Opelka | 6 | 6 | | | | | | | | | | |
| | C Eubanks | 7 | 4 | 4 | 5 | M Mmoh | 4 | 4 | | | | | | | | | | |
| 5 | M Mmoh | 5 | 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 | Semifinals | Semifinals | Semifinals | Semifinals |
| 8 | N Rubin | 6 | 3 | 6 | | | | | | | | | | | | | |
| | E King | 4 | 6 | 3 | 8 | N Rubin | 5 | 6 | 7 | | | | | | | | |
| | A Popyrin | 6 | 7 | | | A Popyrin | 7 | 2 | 5 | | | | | | | | |
| | V Estrella Burgos | 3 | 5 | | | | | | | 8 | N Rubin | 1 | 4 | | | | |
| Alt | E Escobedo | 6$^3$ | 6 | 1 | | | | | | | B Fratangelo | 6 | 6 | | | | |
| Q | S Bangoura | 7$^7$ | 4 | 6 | Q | S Bangoura | 4 | 6 | 5 | | | | | | | | |
| | B Fratangelo | 2 | 6 | 6 | | B Fratangelo | 6 | 1 | 7 | | | | | | | | |
| 4 | V Troicki | 6 | 2 | 0 | | | | | | | | | | | B Fratangelo | 1 | 2 |
| 6 | R Bemelmans | 7 | 7$^8$ | | | | | | | | | | | 2 | D Istomin | 6 | 6 |
| Q | H Nys | 5 | 6$^6$ | | 6 | R Bemelmans | 6 | 6 | | | | | | | | | |
| LL | K Uchida | 6 | 6 | | LL | K Uchida | 3 | 4 | | | | | | | | | |
| WC | T-S Kwiatkowski | 1 | 3 | | | | | | | 6 | R Bemelmans | 3 | 4 | | | | |
| WC | T Paul | 6 | 6 | | | | | | | 2 | D Istomin | 6 | 6 | | | | |
| LL | R Roelofse | 3 | 2 | | WC | T Paul | 5 | 3 | | | | | | | | | |
| | M Arévalo | 4 | 1 | | 2 | D Istomin | 7 | 6 | | | | | | | | | |
| 2 | D Istomin | 6 | 6 | | | | | | | | | | | | | | |