2018 Gerry Weber Open – Singles

Borna Ćorić defeated the defending champion Roger Federer in the final, 7–6(8–6), 3–6, 6–2 to win the singles tennis title at the 2018 Halle Open. It was his first ATP 500 title. With Federer's loss, Rafael Nadal regained the world No. 1 ranking.

Seeds
• # Roger Federer (final)

• #🇩🇪 Alexander Zverev (first round)

• #🇦🇹 Dominic Thiem (second round)

• #🇪🇸 Roberto Bautista Agut (semifinals, retired)

• #🇫🇷 Lucas Pouille (first round)

• #🇩🇪 Philipp Kohlschreiber (second round)

• #🇯🇵 Kei Nishikori (second round)

• #🇫🇷 Richard Gasquet (first round)

Seeds
• # 🇫🇷 Gilles Simon (first round)

• # 🇦🇷 Guido Pella (first round)

• # 🇷🇺 Evgeny Donskoy (first round)

• # 🇮🇹 Matteo Berrettini (qualifying competition, lucky loser)

• # Nikoloz Basilashvili (qualifying competition, lucky loser)

• # 🇨🇦 Vasek Pospisil (first round)

• # Ivo Karlović (first round)

• # 🇷🇺 Mikhail Youzhny (qualified)

Qualifiers
• # 🇩🇪 Matthias Bachinger

• # 🇺🇸 Denis Kudla

• # 🇸🇰 Lukáš Lacko

• # 🇷🇺 Mikhail Youzhny

Lucky losers
• # 🇮🇹 Matteo Berrettini

• # Nikoloz Basilashvili