The exodus of players from next week's Western & Southern Open continued Tuesday as Serena and Venus Williams said they will not play the WTA 1000 event.

The top-ranked American singles player, Sofia Kenin, also said she will skip the Cincinnnati event to focus on preparing for the US Open.

Their withdrawal comes a day after reigning champion Novak Djokovic announced he would not be playing in Cincinnati this year.

Serena Williams, a two-time winner at the event, cited the leg injury she suffered at Wimbledon in explaining her withdrawal. No explanation was provided for her older sister's decision not to play.

World number four Kenin has not played since going out in the second round at Wimbledon, withdrawing from the last two WTA events in San Jose and Montreal due to a lingering foot injury.

“I am rehabbing well in hopes to play the US Open later this month," she said in a statement Tuesday. "I feel another week of recovery is necessary. I want to thank the USTA for all their efforts in holding the event during such challenging times. Best of luck to all the players.”