It took two incredibly close tie-breaks, but Jessica Pegula was ultimately able to find a way past Madison Keys to reach the last four.
Madison Keys, Elina Svitolina and Linda Noskova all progressed into the quarter-finals of the Berlin Open with wins on Thursday.
Elina Svitolina was in a commanding position before Anna Kalinskaya was forced off, with the Ukrainian making a strong start in Berlin.
Madison Keys missed the chance to reach the quarter-finals of the French Open, losing in three sets to rising youngster Diana Shnaider.
No results available
No matches available.
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