Top-seeded Serena Williams withdrew from the Western & Southern Open in Cincinnati with a shoulder injury, tournament officials announced.
Williams, who is the tournament’s two-time defending champion, dropped out on Monday following a morning practice session.
Williams was set to participate in the tournament after being beaten in the first round of the Olympic singles tournament. The men's No. 1 player, Novak Djokovic also withdrew from the Western & Southern Open, citing a wrist injury.
The withdrawal gives No. 2 seed Angelique Kerber a chance to earn the world's top spot if she can win the tournament championship.
Williams, 34, has been ranked No. 1 for the past 183 consecutive weeks. Misaki Doi from Japan replaced Williams in the draw, and received Williams’s first-round bye.
Williams is 33–5 this year in singles competition, winning Wimbledon last month.
– Scooby Axson