ESTORIL, Portugal (AP) — Top-seeded Pablo Carreno Busta defeated fellow Spaniard Tommy Robredo 7-6 (5), 7-5 to advance to the quarterfinals of the Estoril Open on Wednesday, while fifth-seeded Juan Martin del Potro withdrew after the death of his grandfather back home in Argentina.

Del Potro was going to play his second-round match against American Ryan Harrison on Thursday.

"I need to go to my family to be with them during this hard time and say goodbye with them," the former U.S. Open champion said in a statement.

Carreno Busta saved seven break points and converted four of his five break opportunities to win the match in just under two hours.

The 35-year-old Robredo had won all three previous matches against his countryman.

The 21st-ranked Carreno Busta, a semifinalist in Estoril in 2015 and a finalist last year, will play the quarterfinal against defending champion Nicolas Almagro of Spain, who lost only two points on his first serve to defeat Portugal's Gastao Elias 6-1, 6-2.

Second-seeded Richard Gasquet of France defeated Carlos Berlocq of Argentina 6-1, 6-4 for his first tour win since February. The 2015 champion in Estoril underwent appendicitis surgery in March.

Gasquet will play the quarterfinal against South African Kevin Anderson, who rallied to defeat Portuguese qualifier Joao Domingues 5-7, 6-3, 7-5.