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)