Buenos Aires, Argentina (SportsNetwork.com) - Serena and Venus Williams won singles matches Saturday to give the United States a commanding lead in its Fed Cup World Group II matchup against Argentina.

Venus was up first and easily handled Paula Ormaechea, 6-3, 6-2, to give the Americans the first point. Serena, coming off her Australian Open title last weekend, battled through a tough first set before finding her groove in a 7-5, 6-0 victory over Maria Irigoyen.

Serena will try to clinch it for the U.S. on Sunday in the first reverse singles match against Ormaechea. Venus will then take on Irigoyen in the second, while a doubles match is currently slated to pit Americans Taylor Townsend and Coco Vandeweghe against an Argentine pairing of Tatiana Bua and Nadia Podoroska.

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.

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 now a perfect 11-0 lifetime in Fed Cup singles. Venus improved to 16-2 in her Fed Cup singles activity.

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