Elena Rybakina came back from one break down in the second set to beat Veronika Kudemertova 6-4 7-5 after 1 hour and 33 minutes in her opening match at the ecotrans Ladies Open in Berlin.
Rybakina set up a match against former number 1 Veronika Kudemertova in her 10th quarter final of the season.
Rybakina earned the first break to open a 2-0 lead, but she dropped her serve, when she was serving for the set at 5-3. Rybakina broke for the second time in the 10th game to seal the first set 6-4.
Kudemertova built up a 3-1 lead with a break in the first game of the second set. Rybakina broke back at deuce in the sixth game to draw level to 3-3.
Rybakina broke serve on her fourth match point in the 10thgame to reach her first quarter final in Berlin, as Kudemertova was serving to force a tie-break.
Rybakina ended the match with 18 winners to 16 unforced errors.
Rybakina has improved her record to 5-0 against Kudemertova.
Reigning Wimbledon champion and world number 6 Marketa Vondrousova was forced to withdraw from her second round match with a right hip injury. Vondrousova was leading 5-3 in the first set when she slipped and fell on a split-step on the first point of the ninth game.
The Czech player received off-court medical treatment. She returned to play two games before retiring as both players were tied at 5-5.
Vondrousova will have less than two weeks ahead of her title defense at Wimbledon. Kalinskaya will take on either Aryna Sabalenka or Daria Kasatkina in the quarter final.
