Colombian qualifier Robert Farah upset defending champion Nikolay Davydenko 6-3, 6-2 in the opening round of the BMW Open on Tuesday.
The seventh-seeded Russian, who also won the tournament in 2004, dropped serve four times.
Sixth-seeded Mikhail Youzhny of Russia, the 2010 champion, edged out Philipp Petzschner of Germany 7-5, 7-5, and eighth-seeded Marcos Baghdatis of Cyprus outlasted Tobias Kamke of Germany 6-1, 3-6, 6-3 for his first clay-court win of the season.
Baghdatis broke serve four times and saved six of eight break points to advance in a tournament he has twice been a semifinalist.
Also advancing were Sergiy Stakhovsky of Ukraine, Ernests Gulbis of Latvia, Dustin Brown and Matthias Bachinger of Germany, Potito Starace of Italy, Tommy Haas of Germany and Marinko Matosevic of Australia.