Colombia's Santiago Giraldo sent Tommy Robredo packing on Thursday, while two other seeded Spaniards made it safely into the quarter-finals of the US Men's Clay Court Championship in Houston.
Giraldo saved all four break points he faced en route to a 6-3 6-4 victory over second-seeded Robredo, who was making his tournament 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.
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 beat 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."
