Houston - Colombia's Santiago Giraldo sent second-seeded Tommy Robredo packing Thursday, while two other seeded Spaniards made it safely into the quarter-finals of the US Men's Clay Court Championship.
Giraldo saved all four break points he faced en route to a 6-3, 6-4 victory over Robredo, who was making his Houston debut.
"I had a lot of chances in a lot of games, and every time it was 0-30, 15-30, I was hitting three in a row straight to the fence," Robredo said. "With this, there's no chance to win."
It was a different story for third-seeded Spaniard Nicolas Almagro and number four Fernando Verdasco, who both moved into the last eight of the ATP event.
Almagro, last year's runner-up in Houston, cruised past American Michael Russell 6-2, 6-3 while left-hander Verdasco got past American Steve Johnson 6-0, 4-6, 6-3.
Almagro, 28, peppered Russell with seven aces, denying the Houston resident a second quarter-final appearance of the season.
Almagro next faces 21-year-old American Jack Sock, a 6-4, 6-3 winner over Germany's Benjamin Becker.
"I played really good tennis today," Almagro said. "I am happy with my tennis. I played very aggressive."
Verdasco dropped serve just once and converted four of his five break chances against Johnson, who arrived in Houston at a career-high 69th in the world after winning the Le Gosier Challenger last week.
"This is my first match on clay this season," Verdasco said. "I've been just trying to get the rhythm and feel the ball as much as I can. Even when I wasn't playing that well, mentally I was well."
Verdasco next faces 24-year-old American Donald Young, who upset sixth-seeded Juan Monaco of Argentina 6-7 (4/7), 6-4, 6-3.
Colombian Alejandro Gonzalez reached his first ATP quarter-final with a truncated victory over fifth-seeded Spaniard Feliciano Lopez.
Gonzalez was leading 6-3, 2-0 when Lopez retired with severe allergies that he said left him "really sick."
Fernando Verdasco (ESP x4) bt Steve Johnson (USA) 6-0, 4-6, 6-3
Donald Young (USA) bt Juan Monaco (ARG x6) 6-7, (4/7), 6-4, 6-3
Santiago Giraldo (COL) bt Tommy Robredo (ESP x2) 6-3, 6-4
Jack Sock (USA) bt Benjamin Becker (GER) 6-4, 6-3
Alejandro Gonzalez (COL) bt Feliciano Lopez (ESP x5) 6-3, 2-0 - retired
Nicolas Almagro (ESP x3) bt Michael Russell (USA) 6-2, 6-3