2018 Miami Open – Men's singles

John Isner defeated Alexander Zverev in the final, 6–7(4–7), 6–4, 6–4 to win the men's singles tennis title at the 2018 Miami Open. It was Isner's first and only Masters 1000 title, and he became the first new Miami Open champion in nine years.

Roger Federer was the defending champion, but lost in the second round to Thanasi Kokkinakis.

Federer and Rafael Nadal (despite having withdrawn from the event) were in contention for the ATP No. 1 singles ranking. Nadal regained the top ranking as a result of Federer's second-round loss.

With Novak Djokovic and Federer losing their opening matches and Andy Murray and Nadal missing the tournament due to injuries, this was the first time since the 2004 Paris Masters that none of the Big Four won a match at a Masters 1000 tournament.

Seeds
All seeds receive a bye into the second round. • Roger Federer (second round)

• Marin Čilić (fourth round)

• 🇧🇬 Grigor Dimitrov (third round)

• 🇩🇪 Alexander Zverev (final)

• 🇦🇷 Juan Martín del Potro (semifinals)

•  Kevin Anderson (quarterfinals)

• 🇧🇪 David Goffin (second round)

• 🇺🇸 Jack Sock (third round)

• 🇷🇸 Novak Djokovic (second round)

• 🇨🇿 Tomáš Berdych (third round)

• 🇺🇸 Sam Querrey (third round)

• 🇪🇸 Roberto Bautista Agut (second round)

• 🇦🇷 Diego Schwartzman (third round)

• 🇺🇸 John Isner (champion)

• 🇮🇹 Fabio Fognini (third round)

• 🇪🇸 Pablo Carreño Busta (semifinals)

• 🇦🇺 Nick Kyrgios (fourth round)

• 🇫🇷 Adrian Mannarino (second round)

• 🇰🇷 Chung Hyeon (quarterfinals)

• 🇨🇦 Milos Raonic (quarterfinals)

• 🇬🇧 Kyle Edmund (second round)

• 🇷🇸 Filip Krajinović (fourth round)

• 🇱🇺 Gilles Müller (second round)

• 🇧🇦 Damir Džumhur (second round)

• 🇪🇸 Feliciano López (second round)

• 🇯🇵 Kei Nishikori (third round)

• 🇷🇺 Andrey Rublev (second round)

• 🇪🇸 David Ferrer (third round)

•  Borna Ćorić (quarterfinals)

• 🇫🇷 Richard Gasquet (second round)

• 🇪🇸 Fernando Verdasco (fourth round)

• 🇷🇺 Karen Khachanov (third round)

Seeds
• # 🇪🇸 Roberto Carballés Baena (first round)

• # 🇧🇦 Mirza Bašić (qualifying competition, lucky loser)

• # 🇦🇺 John Millman (qualified)

• # 🇧🇷 Rogério Dutra Silva (qualified)

• # Gastão Elias (first round)

• # 🇱🇹 Ričardas Berankis (qualified)

• # 🇮🇹 Matteo Berrettini (first round)

• # 🇯🇵 Taro Daniel (qualifying competition)

• # 🇮🇳 Yuki Bhambri (qualified)

• # 🇬🇧 Cameron Norrie (qualified)

• # 🇺🇸 Bjorn Fratangelo (qualified)

• # 🇧🇪 Ruben Bemelmans (qualifying competition)

• # 🇺🇸 Ernesto Escobedo (qualifying competition)

• # 🇺🇦 Sergiy Stakhovsky (qualifying competition)

• # 🇩🇪 Yannick Hanfmann (first round)

• # 🇧🇷 Thiago Monteiro (first round)

• # Henri Laaksonen (first round)

• # 🇺🇸 Tim Smyczek (first round)

• # 🇸🇪 Elias Ymer (qualifying competition)

• # 🇦🇷 Carlos Berlocq (qualifying competition)

• # 🇨🇦 Peter Polansky (qualifying competition)

• # 🇮🇳 Ramkumar Ramanathan (first round)

• # 🇦🇺 Alex de Minaur (qualified)

• # 🇺🇸 Mackenzie McDonald (qualifying competition)

Qualifiers
• # Darian King

• # 🇺🇸 Michael Mmoh

• # 🇦🇺 John Millman

• # 🇧🇷 Rogério Dutra Silva

• # 🇫🇷 Calvin Hemery

• # 🇱🇹 Ričardas Berankis

• # 🇬🇧 Liam Broady

• # 🇦🇺 Thanasi Kokkinakis

• # 🇮🇳 Yuki Bhambri

• # 🇬🇧 Cameron Norrie

• # 🇺🇸 Bjorn Fratangelo

• # 🇦🇺 Alex de Minaur

Lucky loser
• # 🇧🇦 Mirza Bašić