A dramatic conclusion to an encounter which ebbed and flowed throughout saw both players save match points before Pliskova ultimately prevailed, 4-6, 6-4, 7-6(3).
"I was prepared that I was going to play Venus and that it was going to be tough because all the people were cheering for her," Pliskova said. "It was a great atmosphere. It was my first time here on Arthur Ashe. I really enjoyed the match."
Bidding to become the oldest Grand Slam quarterfinalist in US Open history, Williams produced a courageous display against a player more than a decade her junior. However, despite coming within a point of victory in the final set, she was unable to prevent Pliskova reaching her own career milestone.
Pliskova's failure to reach the second week of a major had long been the anomaly of an otherwise impressive career resume. Having rectified that with a battling win over Anastasia Pavlyuchenkova over the weekend, the Czech played with the kind of confidence that saw her sweep to the Cincinnati title last month.
This belief helped haul her back into the contest and then prevail in the dramatic conclusion. Serving to stay in the match in the deciding set, Pliskova produced a couple of mighty forehand blows to escape from 30-40 down. The drama, though, was only just getting started.
Pliskova proceeded to break for a 6-5 lead, only to squander three match points of her own. The subsequent tie-break saw one final momentum shift, an inspired volley enabling Pliskova to wrest back control and make her way past the finishing post.
"To be honest, it was very difficult after I lost my serve for 6-6. She played a very good game but I was still focused, I put everything in there and I am happy I won it," Pliskova said.
"So far I'm happy that I got my first quarterfinal. I'm going to enjoy the moment and prepare for my next match."
Pliskova reaches the quarterfinals. Entering today, she was the only Top-20 player to have never reached the quarters at a Grand Slam.
? ESPN Stats & Info (@ESPNStatsInfo) September 5, 2016