2004 Mercedes Cup – Singles

Guillermo Coria was the defending champion, but did not participate.

Guillermo Cañas won the title, defeating Gastón Gaudio 5–7, 6–2, 6–0, 1–6, 6–3 in the final.

Seeds
All seeds receive a bye into the second round.

• # 🇩🇪 Rainer Schüttler (second round)

• # 🇦🇷 Gastón Gaudio (final)

• # 🇦🇷 Juan Ignacio Chela (third round)

• # 🇷🇴 Andrei Pavel (third round)

• # 🇨🇿 Jiří Novák (quarterfinals)

• # 🇪🇸 Tommy Robredo (second round)

• # 🇪🇸 Feliciano López (second round)

• # 🇦🇷 Mariano Zabaleta (third round)

• # 🇩🇪 Florian Mayer (second round)

• # 🇷🇺 Mikhail Youzhny (third round)

• # 🇪🇸 David Ferrer (semifinals)

• # 🇪🇸 Albert Costa (quarterfinals)

• # Ivo Karlović (third round)

• # 🇪🇸 Rafael Nadal (quarterfinals)

• # 🇷🇺 Nikolay Davydenko (semifinals)

• # 🇨🇿 Tomáš Berdych (third round)