The top-seeded Russian broke first in both sets but failed to take her chances and was eventually eliminated when she hit a forehand out on match point.

"I played very well. I just played my game, that was my plan," ninth seed Kerber said in a courtside interview after registering her first win over a top-five player.

The world number 27 next meets fellow countrywoman Mona Barthel or Yanina Wickmayer of Belgium.

Sixth seed Julia Goerges of Germany also went out after losing 3-6 7-5 6-1 to Czech Klara Zakopalova.

(Writing by Gregory Blachier, editing by Tony Jimenez)