With No. 1 ranking possibly at risk, Serena Williams takes wild card into Cincinnati

Serena Williams has taken a wild card into the Cincinnati WTA Premier 5 tournament. Williams, who lost to Elina Svitolina in the third round of singles at the Olympic Games, intended to stay through both weeks in Rio and had not originally entered Cincinnati. She also lost with her sister, Venus, in the first round of doubles.

Playing in Cincinnati will give Williams an opportunity to clinch the No. 1 seed for the U.S. Open, which she’ll do if she reaches the quarterfinal round. World No. 2 Angelique Kerber can overtake her in the ranking if she wins the title and Williams loses before the quarterfinals. Williams currently owns a 183-week streak atop the WTA rankings.

The men's field also looks set to have at least one of the tour’s Top 4. Stanislas Wawrinka, who was in doubt with a back injury, has arrived on site. The world No. 4 and his coach Magnus Norman took a photograph on court at Cincinnati:

All eligible ATP players are entered into Masters Series events, and must withdraw if they do not intend to play.