Fourth seed Jeremy Chardy suffered an upset at the Brasil Open as he was beaten 6-4 4-6 7-6 (7/5) by lucky loser Martin Alund in their last-16 clash.
The Frenchman, the only seed in action on Wednesday, was left to rue 16 double faults as he fell to defeat against the unfancied Argentinian in two hours and 36 minutes.
There was a notable win too for another Argentinian, David Nalbandian, who beat qualifier Jorge Aguilar 7-5 5-7 6-3.
Nalbandian, who is also partnering Rafael Nadal in the doubles this week, was making his season debut and booked a last-16 meeting with compatriot Guido Pella.
Albert Montanes beat Paolo Lorenzi 6-4 6-4, while there were also wins for Paul Capdeville and Joao Souza, who both advanced due to retirements.