Delray Beach, Fla. ? Serena Williams completed a sibling sweep Saturday, leaving the U.S. Fed Cup team on the verge of beating Belgium.

Playing Fed Cup for the first time since 2003, Williams beat Caroline Maes, 6-1, 6-4 to give the Americans a 2-0 lead in the best-of-five opening-round match.

Older sister Venus Williams wobbled in the wind but rallied to beat Kirsten Flipkens, 7-5, 6-2. Struggling early with gusty conditions, Venus fell behind 5-3 before winning 11 consecutive points to take charge.

“Down that first set, it’s comforting to know if anything goes wrong, Serena Williams is going to play the second match,” Venus said.

The Americans were heavily favored due to the absence of Belgium’s top players, No. 1-ranked Justine Henin and No. 4 Kim Clijsters, who declined to take part.

Singles matchups will be reversed today, followed by the doubles. The winning team will face the winner of the Russia-Spain match in the semifinals following Wimbledon in July.

Russia took a 2-0 lead over Spain today in Moscow. France and Italy, both playing at home, also took 2-0 leads.

At Moscow, No. 5 Svetlana Kuznetsova and No. 9 Nadia Petrova won for Russia in straight sets. They’re the highest-ranked players competing this weekend among the quarterfinalists.

At Limoges, France, Tatiana Golovin and Nathalie Dechy also won in straight sets. The team advancing will take on Italy or China in the semifinals.

At Castellaneta Marina, Italy, Flavia Pennetta overcame a slow start and a match point to win when Peng Shuai retired because of an injury, 0-6, 7-5, 3-0. Tathiana Garbin edged Sun Tian Tian, 6-4, 2-6, 6-3.