WASHINGTON — Serena Williams said in a Facebook post Saturday that she is taking the next week off to try and heal her right elbow, which she injured while competing at the Swedish Open, forcing her to withdraw from the event.

Williams was scheduled to appear for two matches, one on July 20 playing for the Washington Kastles against the Freedom in Philadelphia, and another against Boston in D.C. on July 21.

“Unfortunately, Serena is injured and won’t be playing this week. We are working to find a replacement and will announce that when we can,” says Jack Deschauer, Senior Vice President of Kastles Media Relations.

The 21-time Grand Slam Champion is trying to accomplish the calendar Grand Slam next month at the U.S. Open but sustained the injury while practicing Thursday and says, “As much fun as we have been having the past eight or so weeks I have to take some time to let my elbow heal.” She added that she is “confident it will be ready for the rest of the summer.”

WTOP’s J. Brooks contributed to this report.