Serena Williams lost the world No. 1 ranking on a double fault

Serena Williams fell in straight sets to 24-year-old Karolina Pliskova in the U.S. Open semifinal on Thursday night, 6-2, 7-6. The loss marks the second consecutive year in which Williams fallsin the semis at the U.S. Open, and ends her quest for a record-setting 23rd grand slamchampionship.With the loss ' which came, frustratingly, on a double fault down 5-6 in the tiebreaker ' Williams also loses the world No. 1 ranking.It's hard to believe that Williams, who earlier this season reached the final of the Australian Open and French Open, and won Wimbledon, could somehow walk away from a semifinal loss with a lower ranking, and yet because of an even better season by Angelique Kerber, Kerber will take over as the new No. 1.Earlier this season, Kerber beat Williams to win the Australian Open, and lost to her in the final at Wimbledon. Now shewill play Caroline Wozniacki in the other semifinal at the US Open, having suddenly become the top player in the world.Williams, meanwhile, ends her 2016 campaign with a disappointing effort against Pliskova. Playing her second match in as many nights, Williams looked out of sorts from the very first game ' particularly when it came to cracking Kliskova's big serve.After a first set won by Pliskova in under 30 minutes, Williams battled in the second set but suffered from too many unforced errors. She began to limp duringthe tiebreaker, and quicklywent down 3-0. After taking a 5-4 lead, it looked, at least for a moment, that Williams still might steal the second set.But she just wasn't good enough for Pliskova, and a double fault to lose the match says it all.Pliskova, who beat Venus Williams earlier in the tournament, had this to say after the match:Pliskova: 'Probably all of America hates me because I beat both sisters Williams."' Jamie Lisanti (@jdlisanti) September 9, 2016Join the conversation about this storyNOW WATCH: Usain Bolt is only 0.1 seconds away from reaching what may be peak human speed in the 100-meter race
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