Serena and Venus Williams are not part of the Fed Cup roster submitted by U.S. captain Mary Joe Fernandez for a World Group playoff against France on April 19-20.
Instead, Fernandez's roster announced on Wednesday includes 18th-ranked Sloane Stephens, No. 42 Madison Keys, No. 49 Varvara Lepchenko and No. 57 Christina McHale.
After losing at a tournament at Charleston, South Carolina, on April 1, top-ranked Serena Williams said: "I'm really just dead. I need some weeks off where I don't think about tennis and kind of regroup."
Venus Williams is ranked 32nd.
The matches will be played on the campus of Saint Louis University. The winning nation will enter the World Group in 2015 and compete for the Fed Cup title. The loser will drop down to World Group II.