British number one Johanna Konta lost 6-3 7-5 to Latvia's world number 26 Anastasija Sevastova in the second round of the Stuttgart Open.
Clay is Konta's weakest surface, while the world number seven has endured a difficult week which included being verbally abused by Romania captain Ilie Nastase in a Fed Cup tie.
Sevastova faces world number five Simona Halep in the next round.
Maria Sharapova is currently playing fellow Russian Ekaterina Makarova.
Former world number one Sharapova is continuing her comeback from a 15-month doping ban.