BERLIN -- Switzerland's Marie-Gaianeh Mikaelian pulled the first upset of the German Open on Monday, beating Japan's Ai Sugiyama 6-1, 7-5 at an event where seven of the world's top 10 are playing.

Sugiyama jumped from 13th to ninth in the seedings after Venus Williams withdrew with an abdominal injury Sunday.

France's Nathalie Dechy, seeded 17th, also reached the second round, defeating Argentina's Clarisa Fernandez 6-0, 6-4.

The loss of Venus and Serena Williams has cost the clay-court tuneup for the French Open two of its biggest draws. Serena Williams withdrew a few months earlier.

Kim Clijsters, a Belgian ranked No. 3, is seeded first. She is followed by No. 4 countrywoman Justine Henin-Hardenne, No. 6 Amelie Mauresmo and No. 7 Jennifer Capriati.

Williams was hurt during her final against Mauresmo in Poland. The Frenchwoman was leading 6-7 (6), 6-0, 3-0. The injury could force Williams from the French Open, which starts in three weeks.

"The injury isn't good,'' Williams said. "They've told me that an abdominal strain needs more time to heal than a regular strain, so I have to take advice and see how I'm doing.''

In other matches, Anca Barna beat Anabel Medina Garrigues 6-4, 6-2; Daja Bedanova downed Anna-Lena Groenefeld 6-2, 6-3; Barbara Schett edged Laura Granville 3-6, 7-5, 6-3; and Elena Likhovtseva routed Henrieta Nagyova 6-1, 6-1.