Paris - Serena Williams and sister Venus helped the United States to a 4-1 victory over Argentina in the Fed Cup on Sunday.
The Americans now advance to the playoffs in April and have a chance to return to the World Group, which comprises the top eight teams.
Venus Williams, who is ranked number 11 in the world, extinguished any Argentinian hope of a comeback as she beat Maria Irigoyen 6-1, 6-4 on Sunday.
Williams needed just 71 minutes to claim victory in the fourth rubber. She bested Paula Ormaechea 6-3, 6-2 on Saturday.
Top-ranked Serena Williams, coming off her 19th Grand Slam singles title at the Australia Open, was rested through illness on Sunday, allowing Ormaechea to keep the Argentines in the tie by defeating substitute Coco Vandeweghe 6-4, 6-4.
However, Serena beat Irigoyen 7-5, 6-0 on Saturday as the US opened up a 2-0 lead on the opening day.
The US will have to wait for February to know the name of their playoff opponents from Italy, Australia, Canada and Poland.