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, Ernests Gulbis, Dustin Brown, Matthias Bachinger, Potito Starace, Tommy Haas and Marinko Matosevic.