ST. LOUIS » Caroline Garcia is still trying to figure out her recent success.

The 20-year-old almost singlehandedly led France to a 3-2 upset of the United States in Fed Cup competition Sunday.

Garcia had a hand in all three of her country’s victories. She beat the USA’s Madison Keys and Sloane Stephens in singles matches early in the meet before joining teammate Virginie Razzano to win the decisive doubles match.

“I’m not sure what I’m doing differently,” she said. “I don’t know. I guess it’s working, so I’ll try to keep doing it, whatever it is.”

France qualified for the World Group in 2015 and will compete for the Fed Cup championship.

The USA is relegated to World Group II for next year.

Garcia and Razzano beat Stephens and Keys 6-2, 7-5 in the fifth and deciding match of the best-of-five, two-day competition held at Chaifetz Arena on the campus of Saint Louis University.

Garcia, ranked 51st in the world, came from out of nowhere to capture her first WTA championships in winning both the singles and doubles titles in the Claro Open Colsanitas in Bogota, Colombia, on April 13.

The Lyon resident carried the momentum from those victories into the Fed Cup.

“She was totally amazing, unbelievable,” France captain Amelie Mauresmo said. “She really rose to the occasion and was fearless.”

Garcia and Razzano used a pair of nifty passing shots to break Stephens’ serve in the 11th game of the second set. The pair won the lengthy 14-point game to take a 6-5 lead. Razzano then served out the match.

Garcia began her run by beating Stephens 6-3, 6-2 in the opening match on Saturday.

“She was the star of the weekend,” USA captain Mary Jo Fernandez said. “I never thought that she got nervous in any of the matches. She’s really aggressive and it’s all coming together.”

France played Sunday without its top player, Alize Cornet, who suffered a groin injury in a three-set loss to Keys on Saturday.

Fernandez took a chance on using Keys and Stephens in the series-deciding doubles match. The duo of Lauren Davis and Christina McHale was originally slated to play.

But Fernandez chose to go with the two singles players even though they were coming off tough matches earlier in the day. Keys had just 35 minutes of rest after her loss to Garcia.

“I was trying to go with the players that had big weapons and (could) impose their game on the French,” Fernandez said.

Said Keys: “Not very often do you finish a match and go out again (35) minutes later. I was a little bit more tired.”