2018 Mutua Madrid Open – Men's singles

Alexander Zverev defeated Dominic Thiem in the final, 6–4, 6–4 to win the men's singles tennis title at the 2018 Madrid Open. He did not lose a set en route to the title, and did not have his serve broken throughout the entire tournament.

Rafael Nadal was the defending champion, but lost to Thiem in the quarterfinals in a rematch of the previous year's final. His defeat ended a 50-set winning streak on clay, the longest single-surface set-winning streak in the Open Era.

Despite his withdrawal from the clay court season, Roger Federer regained the ATP No. 1 singles ranking as Nadal failed to defend his title.

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

• 🇩🇪 Alexander Zverev (champion)

• 🇧🇬 Grigor Dimitrov (second round)

• 🇦🇷 Juan Martín del Potro (third round)

• 🇦🇹 Dominic Thiem (final)

• Kevin Anderson (semifinals)

• 🇺🇸 John Isner (quarterfinals)

• 🇧🇪 David Goffin (third round)

• 🇪🇸 Pablo Carreño Busta (first round)

• 🇷🇸 Novak Djokovic (second round)

• 🇪🇸 Roberto Bautista Agut (second round)

• 🇺🇸 Jack Sock (first round)

• 🇦🇷 Diego Schwartzman (third round)

• 🇨🇿 Tomáš Berdych (first round)

• 🇫🇷 Lucas Pouille (first round)

• 🇮🇹 Fabio Fognini (first round)

Seeds
• # 🇺🇸 Taylor Fritz (qualifying competition)

• # 🇷🇸 Viktor Troicki (qualifying competition)

• # 🇩🇪 Florian Mayer (qualifying competition)

• # 🇫🇷 Pierre-Hugues Herbert (qualifying competition)

• # Nikoloz Basilashvili (qualified)

• # 🇦🇷 Federico Delbonis (qualified)

• # 🇷🇴 Marius Copil (qualified)

• # 🇷🇺 Evgeny Donskoy (qualified)

• # 🇺🇿 Denis Istomin (first round)

• # 🇧🇦 Mirza Bašić (qualifying competition)

• # 🇷🇸 Dušan Lajović (qualified)

• # 🇦🇷 Nicolás Kicker (qualified)

• # 🇰🇿 Mikhail Kukushkin (qualified)

• # 🇷🇺 Mikhail Youzhny (qualifying competition)

Qualifiers
• # 🇦🇷 Nicolás Kicker

• # 🇰🇿 Mikhail Kukushkin

• # 🇷🇸 Dušan Lajović

• # 🇷🇺 Evgeny Donskoy

• # Nikoloz Basilashvili

• # 🇦🇷 Federico Delbonis

• # 🇷🇴 Marius Copil