Tatjana Maria was the first German player to drop out of the French Open in Paris this year.
The 34-year-old from Bad Saulgau, who caused a stir when she won the title in Bogota in April, ultimately had no chance in the 3: 6, 3: 6 against Sorana Cirstea from Romania, who was 26th.
Jule Niemeier (Dortmund) is also in action on the first day of the tournament, with men there are matches between Daniel Altmaier (Kempen) and German number one Alexander Zverev (Hamburg) on the schedule.
For mother-of-two Maria, reaching the third round at Wimbledon 2015 remains her best-ever major tournament performance.