Swiatek battles against Vondrousova to reach Cincinnati semis
The top seed from Poland said she took lessons from a struggling performance in the first set and applied them perfectly in the second to sweep into the final four in a battle of current Grand Slam champions.
Swiatek, the US Open and Roland Garros holder, will play on Saturday for a place in the finals against either US seventh seed Coco Gauff or Italian qualifier Jasmine Paolini.
Swiatek lost serve twice in the opening set as she struggled with the lefty game of her Czech opponent, but broke as Vondrousova served for the set and eventually won a tie-breaker.
She then dominated in the second to claim victory after 93 minutes.
"I'm really happy with the performance," she said. "It's not easy to adjust to her spin.
"After the first set, I was determined to fight for every ball."
Swiatek said the second set was an entirely different story for her.
"I was more focused and I knew what worked," she said. "I learned from the first set. I knew exactly how I should play. That's why it was such a good performance."
Swiatek now stands 2-0 in the series after a victory in Paris three years ago. She was competing in her 12th quarter-final of the season from 13 events played.
