New York, Sep 9 

Top-seeded Serena Williams fell to 10th seeded Czech tennis player Karolina Pliskova in the US Open semifinals on Friday.

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.

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.