Seeded players Gilles Simon of France and Fernando Verdasco of Spain were knocked out in the second round of the Copa Claro on Thursday.

Carlos Berlocq of Argentina beat the third-seeded Simon 6-2, 6-1, and Igor Andreev of Russia downed No. 7 seed Verdasco 7-6 (3), 6-3 at the clay-court tournament.

Argentina's David Nalbandian defeated No. 5 Monaco 6-3, 6-1.

One more seeded player was scheduled to be in action later Thursday with No. 2 Nicolas Almagro of Spain up against Federico Delbonis, another Argentine.

Nobody was better on clay on Thursday than the former Wimbledon finalist Nalbandian, who made few errors.

"I played a great match with lots of intensity from the start," Nalbandian said. "Unfortunately, I don't think Juan had his best day. This is a tournament that all Argentines like to play."

Nalbandian will face fellow Argentine Berlocq in Friday's quarterfinals. In other quarterfinal matchups it will be top-seeded David Ferrer of Spain against Chile's Fernando Gonzalez, and No. 4 Kei Nishikori of Japan facing No. 6 Stanislas Wawrinka of Switzerland.

Andreev will face either Almagro or Delbonis.