Seventh seed Albert Montanes was upset at the Brasil Open on Monday, beaten in straight sets by Italian Filippo Volandri in Sao Paulo.
Spanish veteran Montanes, the world number 51, had no answer for his 30-year-old opponent and suffered a 6-2 6-3 loss.
Portugal's Frederico Gil was another first-round casualty on Monday, going down to world number 184 Javier Marti of Spain 6-2 6-4.
There was better news for local hope Ricardo Mello, who comfortably accounted for Spain's Pere Riba 6-4 6-2 to set up a second-round meeting with another Brazilian, Thomaz Belluci, in the second round.
Jeremy Chardy topped the list of qualifiers who won their way into the main draw on Monday, with the Frenchman joining Paul Capdeville, Igor Andreev and Ruben Ramirez Hidalgo in the field for the ATP 250 event.
Meanwhile Richard Gasquet is through to the second round of the World Tennis Tournament in Rotterdam, but two of the favourites were upset.
Frenchman Gasquet, the fifth seed, took care of Italian Flavio Cipolla with a 6-3 1-6 6-1 victory, and he will meet either Alex Bogomolov Jr or Sergiy Stakhovsky for a place in the quarter-finals of the ATP 500 event.
Fourth seed Feliciano Lopez – the world number 15 - was not as fortunate, upset by Frenchman Paul-Henri Mathieu 4-6 7-6 (7-5) 6-4.
Mathieu is ranked number 733 in the world, but the 29-year-old is on the comeback trail after missing the entire 2011 season with a knee injury.
Sixth-seeded Ukrainian Alexandr Dolgopolov also fell at the first hurdle, being beaten 6-7 (4-7) 6-4 6-2 by Poland's Lukasz Kubot.
To cap off a day of upsets, Dutchman Jesse Huta Galung, ranked 232 in the world, defeated Croatian world number 41 Ivan Ljubicic 7-6 (8-6) 6-3.