NEW YORK — A year after she was stunned here in a US Open semifinal, it happened again to Serena Williams.
This time the upset was crafted by No. 10 seed Karolina Pliskova, a hard-hitting 24-year-old from the Czech Republic, who ended Williams’ most recent run at history 6-2, 7-6 (5).
While the 34-year-old Williams is acknowledged to have the greatest serve ever in the women’s game, it was only the second best on display Thursday night at Arthur Ashe Stadium.
Pliskova, the No. 10 seed, had seven aces and won 84 percent of her first-serve points.
“America probably hates me because I beat Venus and Serena,” Pliskova said after the match.
Pliskova became only the fourth singles player to beat both Serena and Venus Williams in the same Grand Slam event. The others: Martina Hingis, Kim Clijsters and Justine Henin — all retired as multimajor champions.
Williams, who double-faulted on match point, said her left knee, which she thought was injured during a second-round match, was a factor.
“I’m not going to sit here and make an excuse,” she said.
She vigorously disputed the idea she was tired after playing her quarterfinal match Wednesday.
“My mind was just a little bit everywhere, but it was what it was,” Williams said. “Yeah, serious left knee problems. But fatigue had nothing to do with it. If I was tired, I need to find a new career.
“I definitely was not beat up after my quarterfinal match.”
Pliskova’s performance belied her experience. She was playing in her first Grand Slam semifinal, while it was Williams’ 33rd.
“I had a goal today, to beat Serena,” Pliskova said in her on-court interview. “And that’s what I did.
“I don’t believe it. Actually, I do believe it. I knew I could beat anyone if I’m playing my game.”
The tantalizing laundry list of lifetime achievements Williams had within her reach — a record 23 Grand Slam titles and an unprecedented seventh US Open championship — will have to wait until next year.
The No. 1 ranking, which she has held for 186 consecutive weeks, will now go to Angelique Kerber when the new rankings are released Monday.
According to the Westgate Las Vegas SuperBook, Pliskova entered the match as a more than 4-to-1 underdog.
Pliskova will meet the No. 2-seeded Kerber or Caroline Wozniacki, who met later in the second semifinal, in the Saturday afternoon championship final.
Williams looked flat and uninspired throughout the match, possibly due to the fact she was playing for a second consecutive night. Ultimately, that was her responsibility — she asked the USTA to schedule her first match for last Tuesday, which meant playing the quarterfinals and semifinals on successive nights.
Coming off a difficult match with No. 5 seed Simona Halep that she won in three sets, Williams hit only 20 winners, as opposed to 31 unforced errors. She also had a difficult time reading Pliskova’s serve.
“If I’m a professional and I can’t recover, well that’s that,” Williams said.
Information from ESPN’s Ben Fawkes was used in this report.