Buenos Aires, Argentina (SportsNetwork.com) - The United States will play in a Fed Cup World Group II matchup against host Argentina this weekend, with Serena and Venus Williams leading the way for the heavily favored visitors.

Saturday's opening singles in Buenos Aires will pit the former world No. 1 Venus against 121st-ranked Argentine Paula Ormaechea and the currently top- ranked Serena versus 197th-ranked Maria Irigoyen in this best-of-five affair.

The 19-time Grand Slam champ Serena is fresh off her title run at the Australian Open and also the reigning U.S. Open champ.

On Sunday on the red clay at Pilara Tennis Club, Serena is scheduled to meet Ormaechea and Venus will face Irigoyen and a doubles rubber has an American duo of Taylor Townsend and Coco Vandeweghe taking on an Argentine pairing of Tatiana Bua and Nadia Podoroska.

Teenage Aussie Open semifinalist Madison Keys and Varvara Lepchenko were selected for the U.S. team last week, but both opted out this week.

Team USA, captained by Mary Joe Fernandez, is trying to return to the World Group for 2016.

The Americans fell out of the World Group for just the second time since the current format was introduced back in 1995. They must defeat the Argentines then win another series in April to return to the top group next year.

The 33-year-old Serena last played in the Fed Cup in 2013, the previous time the U.S. needed to win to get back into the World Group. She's a perfect 10-0 lifetime in Fed Cup singles.

The 11th-ranked 34-year-old Venus is 15-2 in her Fed Cup singles activity.

The 17-time champion Americans are 3-1 all-time versus Argentina in Fed Cup play.