Anastasia Pavlyuchenkova rallied from a set down to beat Alize Cornet on Wednesday and help the Russian Tennis Federation oust defending champion France and reach the Billie Jean King Cup semi-finals for the first time since 2015.
The RTF team, whose five players in Prague are ranked inside the world's top 40, needed to win just one match in its second round-robin tie in Group A after blanking Canada 3-0 in Tuesday's opener.
Ekaterina Alexandrova lost the first rubber to Clara Burel, leaving Pavlyuchenkova, the highest ranked among the Russian side at 12th, needing to beat the 59th-ranked Cornet to avoid leaving the fate depending on the doubles.
Cornet showed heart against the big-hitting Russian to win the opening set but Pavlyuchenkova found an extra gear and more power to edge a gruelling match 5-7 6-4 6-2 in two hours and 23 minutes.
Pavlyuchenkova broke Cornet's serve three times in the deciding set and converted her first match point with an immaculate drop volley before breaking into a jig with team mate Daria Kasatkina on court.
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"I'm really, really tired right now because I gave it all out there physically and emotionally," Pavlyuchenkova told reporters.
"In the end of the second set I even felt like I didn't have much voice left because I was screaming.
"I didn't feel so great before the match actually, and in the first set I was a bit slow for some reason ... but in the end I found this amazing energy and I was in that sort of zone and vibe."
Burel and Cornet returned to the court for the doubles, hoping to at least help France win the tie but the Russian pair of Liudmila Samsonova and Veronika Kudermetova completely outplayed them in a 6-2 6-1 win.
Under the tournament's new format, 12 teams have been split into four groups of round-robin play and the group winners progress to Friday's semi-finals, with the final on Saturday.
France, which lost its opening clash with Canada 2-1, came into Wednesday's contest trailing the Russians 6-3 in head-to-head meetings.
Alexandrova, ranked 45 places higher than world number 77 Burel, made a strong start in the opening singles rubber before the 20-year-old Frenchwoman launched a superb fightback to win 3-6 6-4 6-3.
Making her singles debut for the 2019 champions, Burel won six consecutive games between the end of the second set and the third set as Alexandrova's unforced errors went up.
Burel sealed victory at the O2 Arena's Centre Court when Alexandrova committed two consecutive double faults.
The Russians, who won the former Fed Cup four times between 2004-2008, will meet Group C winner - the United States - on Friday.
The Americans faced a must-win situation after losing to Slovakia 2-1 in Group C on Tuesday, and Sloane Stephens and Danielle Collins both earned straight-set victories to render the final doubles meaningless.
Stephens beat Nuria Parrizas-Diaz 6-4, 6-4, earning her seventh break of the match in the final game and converting her first match point with a backhand winner.
“I came out really confident, I knew that I’m ready,” said Stephens, the 2017 US Open champion.
Collins secured the second point by easing past Sara Sorribes Tormo 6-1, 6-0 in just under one hour to seal the victory and eliminate Spain.
“I think in this format, every game, every set counts,” Collins said. “For me, I was just on a roll. I think it’s quite hard putting to words when you have a performance like that.”
(With inputs from AP)