The United States will use two teenagers when it plays against Germany in the Fed Cup relegation playoffs this weekend.

Captain Mary Joe Fernandez said Wednesday that 19-year-old Melanie Oudin and 18-year-old Christina McHale will play singles in the best-of-five series on indoor red clay at Porsche Arena.

Bethanie Mattek-Sands is sidelined with an injury and Venus Williams is expected to attend but is not fit to play after a hip injury.

Mattek-Sands, who would have been the highest-ranked American in the squad, will be replaced by Vania King. Liezel Huber completes the foursome.

"We always feel pressure playing Fed Cup. When you are on a team representing your country it's a feeling like no other," Fernandez said. "This is the third time (in U.S. Fed Cup history) that we're in this position to stay in the World Group, and the fact that we are away definitely makes it more challenging.

"But we play every match and do our best. Hopefully we can come out with three victories."

No. 19-ranked Andrea Petkovic leads a German team that includes Julia Goerges, Sabine Lisicki and Anna-Lena Groenefeld.

The United States was runner-up in the last edition of the Fed Cup and has won the competition 17 times, but it could lose its place in the top-tier World Group if it is defeated by Germany.

"They are hungry, they want to prove themselves and they are surely very patriotic," Petkovic said of the American team.

Germany captain Barbara Rittner also warned against underestimating the Americans.

"They are still very dangerous," Rittner said. "Oudin and McHale are two aspiring players that have nothing to lose here."