Japanese eighth seed Ai Sugiyama crashed out of the Porsche Grand Prix with a 6-3 7-6 (7/3) loss to Israel's Anna Smashnova-Pistolesi.
Sugiyama lost the first set before a gritty fightback saw her force a tie-break, which she then surrendered.
Smashnova-Pistolesi is joined in round two by Australian Alicia Molik and Italian Silvia Farina Elia.
The German field will be headed by new world number one Amelie Mauresmo and 2001 champion Lindsay Davenport.
In other matches, Alicia Molik of Australia downed Francesca Schiavone of Italy 6-2 6-3 and Silvia Farina Elia of Italy beat Karolina Sprem of Croatia 3-6 6-3 6-3.