Twice defending champion Tommy Haas was knocked out of the Memphis Championships on Wednesday, losing 3-6, 6-2, 7-5 to fellow German Benjamin Becker.
Haas, who also won the tournament in 1999, lost his serve four times to end his 11-match winning streak at the event.
"Obviously, this is a big win for me," Becker told reporters. "It could have gone either way but I'm fortunate to get the win."
Haas underwent shoulder surgery in November but had appeared to be in fine form in his first-round match.
"I made a few too many unforced errors," Haas told reporters. "He started picking up his game, he started serving better and didn't give me much time to play."
Top-seeded American Andy Roddick won his first-round match in the evening session, downing hard-serving Gilles Muller of Luxembourg 6-4, 7-6.
"He was serving up a storm," Roddick said. "I was lucky to get through."
Fourth seed Radek Stepanek of the Czech Republic beat Florent Serra of France 7-6, 2-6, 7-5 and eighth seed Robin Soderling of Sweden, the 2006 finalist, defeated Canadian qualifier Frederic Niemeyer 6-2, 6-1. Seventh seed Jurgen Melzer of Austria was upset by Steve Darcis of Belgium 6-3, 7-6.
In the women's draw, former world number one and fourth seed Lindsay Davenport of the United States fired 11 aces to beat Russian Evgeniya Rodina 6-1, 6-1 in just 51 minutes.
"It felt good out there," Davenport told reporters. "I've had a lot of success indoors and this has been a good surface for me."
Davenport will next meet sixth seed Caroline Wozniacki of Denmark, a 6-2, 6-4 winner over 15-year-old Michelle Larcher de Brito of Portugal.
Third seed Shahar Peer of Israel also advanced, overcoming Melinda Czink of Hungary 6-0, 3-6, 6-2. She will play qualifier Marina Erakovic of New Zealand, a 7-5, 6-3 winner over American wild card Amber Liu.
