After Yevgeny Kafelnikov was trounced in Friday's singles and took part in a five-set loss in Saturday's doubles, Russian captain Shamil Tarpischev decided to replace the two-time Grand Slam champion with Youzhny, who overcame his nerves to post a 3-6, 2-6, 6-3, 7-5, 6-4 victory on the clay courts of the Palais Omnisports Paris Bercy.
"When I was two sets down I decided to carry on playing my game and see what happened," said Youzhny after the four-hour, 17-minute match. "I felt no emotions at all. I simply could not understand what was happening. And then suddenly I felt pure happiness."
Russia kept alive its hopes of winning the Davis Cup trophy for the first time with Marat Safin's 6-3, 6-2, 7-6 (13-11) defeat of France's Sebastien Grosjean in the first of Sunday's reverse singles matches.
A team had not come back from 2-1 down to win the title since Australia defeated the United States in Cleveland in 1964.
Youzhny, 20, became the first player in the competition's 102-year history to come from down two sets to love down and win a decisive fifth match. Ranked 32nd in the world, he looked out of his element when he went down 0-4 in the second set.
At 0-3 in the second, Youzhny appeared close to tears as he sat with his head in his towel at the change of ends.
But Youzhny regrouped and performed far better than did Kafelnikov, a former world No. 1 who stated early in the year that his main goal was to win the Davis Cup for Russia. Throughout the season, Kafelnikov maintained that if Russia triumphed, he would end his career.
With his focus on the team competition, Kafelnikov's performance during the ATP calendar suffered. He won two events, but finished with his lowest ranking (27) since 1993. He looked slow against Grosjean on Friday and tired in Saturday's doubles.
"Before the match my ego was saying that I should play, but I thought that Mikhail would be able to play better than me," Kafelnikov said. "I thought about the team's interests first. Sometimes it is good to bury your ego in Siberia and put your personal ambitions aside for the well-being of the whole team."
Kafelnikov had almost singlehandedly led Russia to the finals to 1994 and 1995 before Russia lost to Sweden and the United States.
A ball boy at those Davis Cup encounters in his native Moscow, Youzhny began his comeback with a break of serve in the fourth game of the third set.
In the fourth, the Russian fell behind, 4-2, but won the next two games and broke serve in the 12th game. He hit an incredible running backhand winner and Mathieu hit wide to send the match to a fifth set.
Youzhny jumped to a 3-1 lead but allowed the 20-year-old Frenchman back into the set in the sixth game. He bounced back in the next game as Mathieu hit just long on break point, and took a 5-3 advantage with an ace.
With Russia four points away from victory, Youzhny quickly went ahead 40-0 before an overhit service return from Mathieu sparked a celebration by the Russian team.
Youzhny was hoisted in the air by his team and former Russian president Boris Yeltsin stepped out of the crowd of about 15,000 -- 1,500 of them Russians -- to congratulate the nation's new hero.
"Even when we were led two sets to nil, I still believed we could make it," Yeltsin told French television. "Youzhny has a very strong personality and a huge fighting spirit. He proved it today. France has already won while this is the first time for Russia. I was like a mascot for them."
Mathieu, who made his Davis Cup debut Friday in a respectable loss to Safin, was reduced to tears and comforted by his team.
"Paul-Henri has given all he could and he had against a guy who was also ready to give all he had," French captain Guy Forget said. "This defeat is the defeat of the whole group, there is no blame to be made on `Paulo.'
"He was strong. I am sure he will become the key member of our team in the next two years and I am convinced we will win a lot of other Davis Cup trophies with him."
France was aiming for its second straight Davis Cup triumph and 10th overall.
However, the Russian team was jubilant.
"This victory is too great," Safin said. "I feel so happy that is hard to explain with words. We all played well and deserved it so much. Youzhny showed that he was a real Russian man capable of fighting when needed."
And Kafelnikov, who is undergoing surgery Monday to remove a varicose vein from his left leg to alleviate persistent foot pain, said he will rethink his decision to retire over the next few days.
Safin is hoping Kafelnikov sticks around.
"It is great to see that both myself and Mikhail are the future of Russian tennis," the third-ranked player in the world said. "But Yevgeny is only 28 and he is still young. Yevgeny has done so much for Russian tennis.
"Tennis is his life and I think he will decide to stay."