Kerber becomes new world No. 1 after Serena stunned in US Open semis

Angelique Kerber completed quite an accomplishment before even stepping on court Thursday night at the US Open.

With Serena Williams' stunning semifinal defeat at the hands of Karolina Pliskova, Kerber will become the new world No. 1 when the post-tournament rankings get rolled out on Monday. Kerber had a chance to claim the No. 1 spot in August, but failed to beat Pliskova in the Cincinnati finals.

After discovering that she'd surpass Serena, Kerber went out and soundly beat Caroline Wozniacki in the other semi, to advance to her third major final of the year.

At 28 years and 238 days old, Kerber will become the oldest women's player ever to debut at No. 1. The previous record holder was Jennifer Capriati, who was 25 years and 200 days old when she ascended to the top spot in 2001.

Serena could have broken Steffi Graf's record for consecutive weeks at No. 1, but instead she and Kerber's countrywoman will share the mark at 186 weeks.