Top-seeded Nicolas Almagro of Spain, fresh from winning the Brazil Open, advanced to the second round of the clay court Copa Claro with a 6-1, 6-2 victory over Pablo Galdon of Argentina on Tuesday.
Second-seeded Stanislas Wawrinka of Switzerland also advanced, beating Carlos Berlocq of Argentina 6-4, 3-6, 6-3.
Fifth-seeded Juan Monaco of Argentina joined the list of seeded winners when he topped Ivan Navarro of Spain 6-2, 7-6 (2).
In late matches, No. 3 David Nalbandian of Argentina beat Potito Starace of Italy, 6-4, 6-4; and No. 7 Alexandr Dolgopolov of Ukraine lost to Jose Acasuso of Argentina 6-2, 6-4.
Other first-round winners Tuesday included Juan-Pablo Brzezicki of Argentina, Albert Ramos-Vinolas of Spain, Eduardo Schwank of Argentina, Pablo Cuevas of Uruguay, Horacio Zeballos of Argentina, and Victor Hanescu of Romania.