Emma Raducanu's first clay-court match of the season ended in a one-sided defeat by former French Open champion Jelena Ostapenko in Stuttgart.
The British number one struggled to deal with ferocious hitting from the Latvian and lost 6-2 6-1 in 59 minutes.
Having reached the quarter-finals of the event last year, Raducanu's exit means she will drop down the rankings from her current place of 68.
Ostapenko will play Tunisia's third seed Ons Jabeur in the last 16.
Raducanu skipped Great Britain's Billie Jean King Cup defeat to France last week to prepare for the clay-court swing but was completely outplayed after being given a tough opening draw.