Japan's Naomi Osaka was knocked out in the quarterfinals of the Madrid Open on Thursday, leaving the door open for a potential loss of the world's top ranking.

Osaka fell 3-6, 6-2, 7-5 to Switzerland's Belinda Bencic, who goes on to face Romanian Simona Halep in the semifinals. Halep will regain the No. 1 ranking from Osaka if she wins the title in Madrid.In the men's draw, world No. 7 Kei Nishikori was defeated by Stan Wawrinka of Switzerland in straight sets 6-3, 7-6(3) in their third round match.READ FULL ARTICLE