Racket Response: Serena Williams out of the Open, loses No. 1 ranking

— -- NEW YORK -- A year ago, this was precisely the time and place Serena Williams crashed and burned.

She was attempting the rare calendar-year Grand Slam, having won her first 26 major matches of the season in Melbourne, Paris, Wimbledon and through the quarterfinals in New York.

And then Williams was blindsided by Roberta Vinci of Italy, playing in her first Grand Slam semifinal. The pressure that had been building all year -- pressure Williams had flatly dismissed -- seemed to paralyze her.

This year, with milestones of a more cumulative sort on the line, Williams had been noticeably calmer -- until Thursday night. But playing against Karolina Pliskova, a 24-year-old from the Czech Republic, there were times when the same looks of dread and absolute anguish that surfaced against Vinci again crossed her features.

The No. 10-seeded Pliskova produced an emphatic 6-2, 7-6 (5) victory to advance to Saturday's final against the winner of the late match between No. 2 seed Angelique Kerber and two-time US Open finalist Caroline Wozniacki.

Williams wasn't just a victim of nerves; as the match progressed she seemed troubled by a left hamstring injury that had her hobbling into the tiebreaker.

"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."

A few more takeaways from this stunner:

Pliskova never, ever blinked: Down a set and 15-30 in the opening game of the second, Williams desperately needed to change the momentum of her swiftly vanishing match against Pliskova. So she cracked a forehand right at Pliskova's midsection, who was lucky to barely deflect it with her racket. Williams let out a huge roar, but Pliskova wasn't impressed. She hung on to force a second-set tiebreaker and closed the deal there -- just as she had done earlier against Serena's sister Venus. "America probably hates me," she said, "because I beat Venus and Serena."

Williams was physi cally compromised: Williams did not move particularly well throughout the match, possibly because she was playing for a second consecutive night. Ultimately, that was her responsibility because she asked the USTA to play her first match last Tuesday, which meant playing the quarterfinals and semifinals on successive nights. Coming off a difficult match against No. 5 seed Simona Halep that she won in three sets, Williams seemed to be increasingly troubled by a left knee injury. Her deteriorating footwork and her tight forehand didn't help, either.

This was a coming-out party: While Williams was going for a handful of cherished records, Pliskova played with a grit and style that belied her lack of major experience. This was her first Grand Slam semifinal, while Williams has now appeared in 33. Pliskova is the first Czech woman to reach the US Open final since 1993, when Helena Sukova did it. She's on a career-best 11-match winning streak. And to think, she had never been past the third round of a major. Pliskova has now beaten five top-10 players this year -- including all three 2016 Grand Slam winners: Svetlana Kuznetsova, Garbine Muguruza, Kerber, Venus Williams and Serena Williams.

Serena needs a vacation: After losing to Vinci a year ago, Williams shut it down for the rest of the season. It worked, and she won a Slam this year and got to another final. Williams, who turns 35 at the end of the month, might want to consider that again.