In the US Open, in a major upset top seed Serena Williams was stunned by 10th seeded Karolina Pliskova of Czech Republic. In the first women's singles semi-final, current world number one Serena was battling for a place in Final as Karolina 12th ranked ousted her 6-2, 7-6 and 7-5. Pliskova has booked her maiden Final appearance, before this she had never moved ahead of the 3rd round in a Grand Slam event. Serena not only lost her chance to win 23rd Major title and move past Stefi Graff but she will surrender her number one position after 186 consecutive weeks.Meanwhile, in the other semi-final, 2nd seeded German Angelique Kerber defeated Danish Caroline Wozniacki, 6-4, 6-3. She will meet Karolina in the summit clash.