Rankings Watch: Serena Williams hits a No. 1 milestone, Halep up to No. 2

This week Serena Williams hits her 114th consecutive week at No. 1, tying her with Chris Evert for the third longest streak in WTA history. Serena now sits behind only Steffi Graf's record mark of 186 consecutive weeks and Martina Navritlova's mark of 156 weeks. 

Serena cemented her comeback from serious illness and injury by retaking the No. 1 ranking on February 18th, 2013. Since then she has been the consummate front-runner. She has lost just ten matches since then, compiling a 138-10 record. Only eight players have been able to beat her in the last two years. Her current reign at No. 1 is the longest of her career.

WTA

In other rankings news, Romania's Simona Halep is back at a career-high No. 2 after Maria Sharapova failed to defend her title in Stuttgart. Sharapova slips to No. 3. The swap in rankings means Halep will be seeded No. 2 at next week's Madrid Open.

Stuttgart champion Angelique Kerber is up to No. 12 behind her compatriot Andrea Petkovic. The biggest WTA mover of the week was Delaware's Madison Brengle, who moved up seven spots from No. 43 to No. 36 after making the Stuttgart semifinals. 

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On the ATP side, Rafael Nadal holds on to his No. 4 ranking for now, with Barcelona Open champion Kei Nishikori hot on his heels at No. 5. Theirs is an important rankings battle over the next three weeks as they vie for the No. 4 seed at the French Open.

Bucharest Open champion Guillermo Garcia Lopez jumped 14 spots to No. 31, putting him in good position to earn a seed in Paris. Pablo Andujar, the runner-up in Barcelona, is the biggest mover in the Top 100, up 24 spots to No. 42. On the flip side, Santiago Giraldo, who made the Barcelona final last year, tumbled 19 spots to No. 50. 

21-year-old Jiri Vesely continues to build his ranking up as well. The Czech made his second final of the season at the Bucharest Open and is up eleven spots to No. 35. And in more encouraging news for an ATP youth movement, 18-year-old Hyeong Chung makes his Top 100 debut after winning the Savannah Challenger, landing at No. 88. He is one of two teenagers in the ATP's Top 100, with the other being No. 55 Borna Coric.