In-form teenager Mirra Andreeva went out of the Stuttgart Open as she lost in straight sets to fellow Russian Ekaterina Alexandrova in the last 16.
Sixth seed Andreeva, who has already won two titles this season, lost 6-3 6-2 against unseeded Alexandrova in just over an hour.
Andreeva, 17, became the youngest champion at a WTA 1000 event in February by winning the Dubai Tennis Championships, before triumphing at Indian Wells in March.
But she was unable to wrestle control of the match from Alexandrova, 30, who claimed her fourth win over a top-10 player this season.