2013 U.S. Men's Clay Court Championships – Singles

Juan Mónaco was the defending champion, but lost to John Isner in the semifinals.

Isner went on to win the title, defeating Nicolás Almagro in the final, 6–3, 7–5.

Seeds
The top four seeds received a bye into the second round. • # 🇪🇸 Nicolás Almagro (final)

• # 🇩🇪 Tommy Haas (second round)

• # 🇦🇷 Juan Mónaco (semifinals)

• # 🇺🇸 Sam Querrey (withdrew because of a right pectoral muscle strain)

• # 🇺🇸 John Isner (champion)

• # 🇪🇸 Fernando Verdasco (second round)

• # 🇮🇹 Paolo Lorenzi (quarterfinals)

• # 🇺🇸 Michael Russell (first round)

Seeds
The top five seeds receive a bye into the second round. • # Ivo Karlović (qualifying competition, lucky loser)

• # 🇩🇪 Mischa Zverev (second round)

• # 🇷🇺 Teymuraz Gabashvili (qualifying competition)

• # 🇺🇸 Bradley Klahn (qualified)

• # 🇨🇦 Peter Polansky (qualifying competition)

• # 🇦🇷 Facundo Argüello (qualified)

• # 🇺🇸 Michael Yani (first round, retired)

• # 🇺🇸 Alex Kuznetsov (first round)

Qualifiers
• # 🇦🇹 Gerald Melzer

• # 🇺🇸 Robby Ginepri

• # 🇦🇷 Facundo Argüello

• # 🇺🇸 Bradley Klahn

Lucky losers

 * 1)  Ivo Karlović