SAN ANTONIO, TX, USA -- The United States retained its spot in the Fed Cup World Group as the American team got two Sunday singles victories -- one from an established veteran and another from a rising star -- to knock off four-time Fed Cup champion Switzerland by 3-1.

2017 US Open champion Sloane Stephens opened the day with a 6-3, 6-2 victory over Viktorija Golubic, giving the Americans a 2-1 lead after they had split the Saturday singles with Switzerland. World No.8 Stephens, competing in her seventh Fed Cup tie this weekend, improved her singles record at the premier team event to 5-4.

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Following that, Sofia Kenin survived a topsy-turvy second set to oust former Top 10 player Timea Bacsinszky, 6-3, 7-6(4), and clinch the tie for the home team. Kenin, a last-minute substitute for Madison Keys, picked up her first Fed Cup singles win in four attempts.

By guaranteeing themselves a spot in next year's top tier, the United States have immediately put themselves in the running for a 19th Fed Cup title, having won the event as recently as 2017.

In the first singles clash of the day, Stephens started in some early trouble, falling behind 0-40 on her serve at 1-1. However, Stephens maneuvered out of that jam, winning five straight points, to hold her serve. The American was rewarded with a break in the following game, claiming a 3-1 lead following a Golubic forehand error.

World No.80 Golubic got back on serve at 4-3, but the Swiss player squandered any momentum in the next game, as she let a 40-0 lead go begging and was broken by Stephens after a netted backhand miscue. Stephens would not yield at that juncture, and converted her second set point at 5-3 after another long unforced error from the racquet of Golubic.

After saving a break point and holding for 2-2 in the second set, Stephens jumped on Golubic to take control of the second set. The Swiss player double faulted on break point to drop serve and cede a 3-2 lead to Stephens, and Golubic was never able to pull herself back into the tilt from that point forward.

Stephens won the final five games of the match to close out the victory after 79 minutes of play, putting her American team up by two matches to one in the tie. Stephens had 17 winners to 15 for Golubic, while Golubic outpaced Stephens in unforced errors by 30 to 22.

With the Americans leading, World No.36 Kenin was determined to notch her first Fed Cup win, now that she was subbed in for Keys. Kenin suffered two excruciatingly narrow losses to Barbora Strycova and Katerina Siniakova in the 2018 Fed Cup final, as her team fell to the Czech Republic.

The signs were strong for the American in the first set. After both players held with ease through the first seven games, Kenin earned the first break points of the match at 4-3, and grabbed the break after one of her solid backhands forced an error from two-time French Open semifinalist Bacsinszky. Serving for the set at 5-3, Kenin closed out her one-set lead after Bacsinszky sent a service return long.

Brilliant Bacsinszky backhands gave the Swiss star a solid 3-0 lead in the second set, and it appeared that a decider would be in the offing. But Kenin continued to grind out rallies in her favor as the set progressed, and got back level at 3-3.

Bacsinszky then broke again for 5-3, taking the Kenin serve on her fifth break point of a lengthy game. Kenin, though, punched a volley to break back immediately, and after a love hold, rang up a second straight break to lead 6-5. However, Kenin blinked when serving for the match after that turnaround, and Bacsinszky bossed the American around with more blistering backhands, breaking serve for 6-6.

In the tiebreak, Kenin jumped out to a huge lead, with big serves and a forehand down-the-line winner putting her ahead 4-0. Bacsinszky double faulted to cede a 5-0 lead to Kenin, and the American held five match points at 6-1. Three of those match points went begging, but Bacsinszky plopped a forehand into the net on the fourth, and Kenin earned her maiden Fed Cup victory, winning the tie in the process.