2018 Western & Southern Open – Men's singles

Novak Djokovic defeated Roger Federer in the final, 6–4, 6–4 to win the men's singles tennis title at the 2018 Cincinnati Masters. With this win, he became the first player to complete the career Golden Masters (winning all nine ATP Masters 1000 tournaments over the course of a career) in singles.

Grigor Dimitrov was the defending champion, but lost to Djokovic in the third round.

Seeds
The top eight seeds receive a bye into the second round. • 🇪🇸 Rafael Nadal (withdrew)

• Roger Federer (final)

• 🇩🇪 Alexander Zverev (second round)

• 🇦🇷 Juan Martín del Potro (quarterfinals)

• 🇧🇬 Grigor Dimitrov (third round)

• Kevin Anderson (third round)

• Marin Čilić (semifinals)

• 🇦🇹 Dominic Thiem (withdrew)

• 🇺🇸 John Isner (first round)

• 🇷🇸 Novak Djokovic (champion)

• 🇧🇪 David Goffin (semifinals, retired)

• 🇦🇷 Diego Schwartzman (first round)

• 🇪🇸 Pablo Carreño Busta (quarterfinals)

• 🇬🇧 Kyle Edmund (second round)

• 🇦🇺 Nick Kyrgios (third round)

• 🇫🇷 Lucas Pouille (second round)

Seeds
• # 🇦🇺 John Millman (first round, retired)

• # 🇺🇸 Ryan Harrison (first round)

• # 🇹🇳 Malek Jaziri (qualifying competition, lucky loser)

• # 🇺🇸 Tennys Sandgren (first round)

• # 🇷🇸 Dušan Lajović (qualified)

• # 🇬🇧 Cameron Norrie (first round)

• # 🇷🇺 Daniil Medvedev (qualified)

• # 🇪🇸 Feliciano López (first round)

• # 🇪🇸 Guillermo García López (qualifying competition, lucky loser)

• # 🇯🇵 Yūichi Sugita (first round)

• # 🇺🇸 Denis Kudla (qualified)

• # 🇯🇵 Taro Daniel (first round)

• # 🇧🇦 Mirza Bašić (first round)

• # 🇸🇰 Jozef Kovalík (first round)

Qualifiers
• # 🇺🇸 Michael Mmoh

• # 🇵🇱 Hubert Hurkacz

• # 🇺🇸 Denis Kudla

• # 🇺🇸 Bradley Klahn

• # 🇷🇸 Dušan Lajović

• # 🇷🇴 Marius Copil

• # 🇷🇺 Daniil Medvedev

Lucky loser
• # 🇹🇳 Malek Jaziri

• # Guillermo García López