ESTORIL: Fourth-seeded David Ferrer of Spain defeated Frederico Ferreira Silva of Portugal 6-3, 6-4 to reach the quarter-finals of the Estoril Open on Thursday. Ferrer broke serve twice in each set against the 426th-ranked Silva to win his 697th career match. He will meet Ryan Harrison of the US, who advanced on Wednesday after fifth-seeded Juan Martin del Potro withdrew because of the death of his grandfather in Argentina. Third-seeded Gilles Muller of Luxemburg defeated Pedro Sousa of Portugal 6-3, 6-2.