Munich, Germany:Sebastien Grosjean upset top-seeded Tommy Haas 6-4, 6-4 in the first round of the BMW Open on Tuesday.
Seventh-seeded Guillermo Canas retired with abdominal muscle problems while leading 6-4, 1-2 against Nicolas Devilder of France.
Canas, who has beaten top-ranked Roger Federer twice this year, lost to Rafael Nadal in the final in Barcelona on Sunday.
Second-seeded Tomas Berdych eased past Florian Mayer 6-2, 6-1.
Also, German wild-card Alexander Waske beat sixth-seeded Radek Stepanek 7-6 (3), 6-3; and fifth-seeded Jarkko Nieminen had a break of serve in each set to defeat Rainer Schuettler 6-4, 6-4.
Waske, a big-serving doubles specialist, had 11 aces to earn his first singles win this year.
Benjamin Becker, Nicolas Massu and Raemon Sluiter also advanced to the second round of the clay-court tournament.
Becker beat qualifier Nenad Zimonjic 7-6 (6), 6-3; Massu routed Thomas Johansson 6-2, 6-1; and Sluiter rallied to defeat Jan Hajek 3-6, 6-2, 7-6 (5).