Robredo defeated Italian Potito Starace 5-7, 6-3, 6-3. His fellow Spaniard Almagro lost to countryman Oscar Hernandez 6-2, 1-6, 6-3 and Spaniard Moya lost to Argentine Maximo Gonzalez 6-4, 6-4. Moya, a former world No. 1, took the title in this tournament in 2003.
Sixth-seeded Spaniard Albert Montanes also lost, 6-2, 6-3 to unranked Argentine Martin Vassallo.
Last year's Buenos Aires runner-up, fifth-seeded Argentine Jose Acasuso, beat Spanish qualifier Daniel Munoz-De La Nava 6-2, 7-6 (7-4). Seventh-seeded Spaniard Marcel Granollers beat last week's Costa do Sauipe runner-up to Robredo, Brazilian Thomaz Bellucci, 7-5, 7-5.