2011 Estoril Open – Men's singles

Albert Montañés was the defending champion, but chose to compete in the Serbia Open instead.

Juan Martín del Potro defeated Fernando Verdasco 6–2, 6–2 to claim his 2nd title this year since rehabilitating from wrist surgery, and his first on clay in nearly three years. It was Del Potro's ninth career title.

Seeds
The top four seeds received a bye into the second round. • # 🇸🇪 Robin Söderling (quarterfinals)

• # 🇪🇸 Fernando Verdasco (final)

• # 🇫🇷 Jo-Wilfried Tsonga (second round)

• # 🇫🇷 Gilles Simon (quarterfinals)

• # 🇨🇦 Milos Raonic (semifinals, retired due to back injury)

• # 🇧🇷 Thomaz Bellucci (quarterfinals)

• # Kevin Anderson (quarterfinals)

• # 🇦🇷 Juan Martín del Potro (champion)