Serena Williams will make her only World TeamTennis appearance with the defending champion Washington Kastles on July 22 before heading to the London Olympics.
The WTT schedule was announced Wednesday. Williams will play in D.C. against the Kansas City Explorers.
Lindsay Davenport and the Orange County Breakers will host the Kastles at the UC Irvine campus July 9 to open the 37th WTT season.
Venus Williams of the Kastles will face Martina Hingis of the New York Sportimes on July 23 in Albany, N.Y., and play a home match the next night.
John Isner returns to the Boston Lobsters on July 23 against Philadelphia and will play July 24 in Albany.
The eight-team league runs from July 9-28, with the WTT finals Sept. 14-16 in Charleston, S.C.