BRISBANE, Australia - Even without Serena and Venus Williams, the United States was too strong for Australia in their Fed Cup playoff, clinching a spot in the elite eight-nation World Group next year with wins in the first three singles matches.

Coco Vandeweghe filled in for Madison Keys in the opening reverse singles match on Sunday and came from a set and a break down to beat Australian No. 1 Sam Stosur 2-6, 7-5, 6-4 to give the Americans an unbeatable 3-0 lead in the best-of-five playoff on temporary indoor clay court at Pat Rafter Arena.

Vandeweghe saved two breakpoints in the last game before closing with a service winner.

For the second time in as many matches, former U.S. Open champion and French Open finalist Stosur melted down after winning the first set.

Surprise pick Christina McHale beat Stosur 3-6, 6-1, 7-5 on Saturday to give the United States a 2-0 lead after Madison Keys opened with a 6-4, 6-2 win over Daria Gavrilova, who was making her Fed Cup debut for Australia.

Vandeweghe was unsettled in the first set on Sunday, dropping serve twice, but picked up rhythm as the match progressed and exploited the tension evident in the must-win situation for Stosur.

The U.S. travelled to Australia without its leading three singles players, with the Williams sisters and Sloane Stephens skipping the playoff and leaving No. 25-ranked Keys as the highest-ranked player on the team.