Serena Williams is on the U.S. Fed Cup roster for matches against Ukraine on April 21-22, but her sister Venus is not.
"She just played Miami and Charleston, so she's trying to gauge now her recovery, how much she can play," U.S. Fed Cup captain Mary Joe Fernandez said Wednesday about Venus. "She's, I believe, planning on playing a couple of tournaments now before the French Open."
Venus recently returned to action after being sidelined for more than six months. She was diagnosed with an autoimmune disease, Sjogren's syndrome.
Joining Serena, a 13-time Grand Slam champion, on the team picked by Fernandez were Christina McHale, Sloane Stephens, and Liezel Huber.
The best-of-five-match series will be on clay at Kharkiv, Ukraine.
The country that wins will be promoted into the main Fed Cup group in 2013 and be able to compete for the title. The loser will drop into World Group II.
Serena Williams is making her second consecutive Fed Cup appearance after winning twice against Belarus in February to improve to 6-0 in singles play in the team competition.
"For me, obviously it's a big bonus to have someone like Serena there, not only in terms of [how] your chances increase tremendously, but the effect she has on the rest of the team, what she brings to the table with motivation, the work ethic, how she talks to the players," Fernandez said. "I think it really just is priceless."