Top-seeded Serena Williams fell to 10th seeded Czech tennis player Karolina Pliskova in the US Open semifinals on Friday.
It is for the second consecutive year, Williams bowed out in the semifinals of the US Open.
Williams double faulted on match point in a second-set tie-break to give Pliskova the match. With Pliskova's 6-2 7-6 straight sets win, Williams' 186-week reign as world No 1 (stretching back to February 18, 2013) is now over.
The 24-year-old Pliskova, who had never before made it past the third round of a major, becomes the first person to best both Williams sisters at the same Slam since Kim Clijsters did so in 2009.
Williams fell behind by a quick 3-0 in the breaker but rallied back to three-all with two miniholds and a double fault by Pliskova.
The match came to an end as the American lost with a double fault to fall in the semis of the US Open for the second straight year.