(dpa) - German Denis Gremelmayr earned his first quarter-final in more than three frustrating months with a 7-5, 7-5 win over fourth seed Feliciano Lopez on Wednesday at the Los Angeles Classic.
The number 89 has a point to prove to national sports authorities, after he was overlooked in favour of Rainer Schuettler by the German Olympic Committee for a late place at the Beijing Games.
Gremelmayr improved to 12-14 this season, next facing a match against either two-time Grand Slam champion Marat Safin or US player Wayne Odesnik.
He last appeared in the quarters of a tournament in May in Barcelona, where he lost a semi-final to Rafael Nadal at the Spaniard's home event.
Meanwhile, Spaniard Fernando Verdasco, seeded second, handed over 10 double-faults including one on match point as France's Florent Serra advanced 6-2, 7-6 (7-4) into the last eight.
"His doubles certainly helped me. He started the match well, but so did I," said the winner.
Serra is back on form after winning just one game a week ago in a second-round loss to Nadal in Cincinnati, Ohio.
The number 75 said that he only got word shortly before the Cincinnati start that he was into the field. He was forced to cut short a European holiday and reached North America only two days before his match.
"I didn't play well," Serra said. "But Nadal gives you absolutely no points, and most balls are above your shoulder. It was tough."
Andy Roddick is top seed at the Los Angeles event, which has been cut to 28 men due to the start of the Beijing tournament.