2013 Citi Open – Men's singles

Alexandr Dolgopolov was the defending champion, but lost to Indian qualifier Somdev Devvarman in the second round.

Juan Martín del Potro won his third Citi Open title and second title of the year, defeating John Isner in the final, 3–6, 6–1, 6–2.

Seeds
All seeds received a bye into the second round. • # 🇦🇷 Juan Martín del Potro (champion)

• # 🇯🇵 Kei Nishikori (third round)

• # 🇩🇪 Tommy Haas (semifinals)

• # 🇨🇦 Milos Raonic (third round)

• # 🇫🇷 Gilles Simon (second round)

• # 🇺🇸 Sam Querrey (third round)

• # Kevin Anderson (quarterfinals)

• # 🇺🇸 John Isner (final)

• # 🇺🇦 Alexandr Dolgopolov (second round)

• # 🇪🇸 Feliciano López (withdrew because of fatigue)

• # 🇧🇬 Grigor Dimitrov (quarterfinals)

• # 🇫🇷 Julien Benneteau (second round)

• # Ivan Dodig (third round)

• # 🇦🇺 Bernard Tomic (third round)

• # 🇷🇺 Nikolay Davydenko (second round)

• # 🇨🇾 Marcos Baghdatis (quarterfinals)

• # 🇫🇷 Michaël Llodra (second round)

Seeds
• # 🇦🇺 Matthew Ebden (qualified)

• # 🇺🇸 Rhyne Williams (qualifying competition, lucky loser)

• # 🇺🇸 Tim Smyczek (qualified)

• # 🇨🇦 Jesse Levine (qualifying competition, lucky loser)

• # 🇮🇳 Somdev Devvarman (qualified)

• # 🇺🇸 Alex Kuznetsov (qualified)

• # 🇺🇦 Illya Marchenko (first round)

• # 🇯🇵 Yūichi Sugita (qualified)

• # 🇺🇸 Donald Young (first round)

• # 🇹🇳 Malek Jaziri (qualifying competition)

• # 🇺🇿 Farrukh Dustov (first round)

• # 🇦🇺 Samuel Groth (qualified)

Qualifiers
• # 🇦🇺 Matthew Ebden

• # 🇦🇺 Samuel Groth

• # 🇺🇸 Tim Smyczek

• # 🇯🇵 Yūichi Sugita

• # 🇮🇳 Somdev Devvarman

• # 🇺🇸 Alex Kuznetsov

Lucky losers
• # 🇺🇸 Rhyne Williams

• # 🇨🇦 Jesse Levine