Back with the French team, Jo-Wilfried Tsonga earlier sent his country to its 18th final by defeating Serbia's Dusan Lajovic 2-6, 6-2, 7-6 (5), 6-2 in Lille. Around 100 kilometers (62 miles) away in Brussels, Belgium recovered from a 2-1 deficit on the indoor clay of the Palais 12.
France will host the final from Nov. 24-26 on a surface yet to be announced. With Tsonga's win, the French reached an unassailable 3-1 lead and the teams decided against playing the final rubber. Belgium trailed after Saturday's doubles but managed to turn things around in front of a buoyant crowd. David Goffin first rallied past Nick Kyrgios 6-7 (4), 6-4, 6-4, 6-4 before Steve Darcis defeated Jordan Thompson 6-4, 7-5, 6-2.
"It was so tough in the beginning," said Belgium captain John van Herck. "Kyrgios was so tough, but David hung in and I think from then on we changed a little bit the momentum. It was a career-defining win for David. The way he played was unbelievable. All credit to Kyrgios and Thompson but I think we played unbelievable tennis."
Goffin, who had not beaten Kyrgios in three previous matches, returned well and played astute tennis to counter his opponent's big shots, extending his excellent Davis Cup record to 15 wins from 16 singles matches.
Goffin dropped his serve only once and fell onto his back after hitting two aces in succession to serve out the match after a three-hour battle. "Everything is in the timing, I think," Goffin said about his returns, adding "I see the ball earlier than the others so maybe that's why I have a good return."
Darcis was set to take on John Millman in the decisive rubber but Australia captain Lleyton Hewitt changed his lineup to send Thompson instead. The move did not pay off as Darcis put on a dominant display, converting five of seven breakpoints. He hit 34 winners and sealed the match on his first chance with a backhand volley that hit the net cord.
France avenged its loss to Serbia in the 2010 final and qualified for its first final since losing to Switzerland three years ago. France won the last of its nine titles in 2001 against the Australians while Belgium will be chasing its first trophy in the team event after losing two finals.
"I'm relieved and happy," said France captain Yannick Noah. "To win the Davis Cup is something extraordinary. Hopefully I will be able to win it with these lads." Noah already captained France to the 1991 and 1996 Davis Cup titles, and has not lost a final as team captain. As a player, he also won the French Open in 1983.
The French did a lap of honor after Tsonga won the decisive point against a depleted Serbian team that gave the hosts a tough challenge. Tsonga won his second point for France after defeating 22-year-old debutant Laslo Djere in straight sets on Friday to level the tie at 1-1. Two-time Grand Slam champions Nicolas Mahut and Pierre-Hugues Herbert then gave the hosts a 2-1 lead when they beat Filip Krajinovic and Nenad Zimonjic in the doubles match.
Tsonga, who had decided to skip the Davis Cup this year, changed his mind and made a successful return to the French team. He was overpowered by his rival in the first set but improved and recovered in the second by upping his game when it mattered, after a double fault from Lajovic gave him an early break.
The third set was close with neither player giving in on the red clay of the Pierre Mauroy stadium. Lajovic was the first to crack despite saving two set points in the tiebreaker when he dumped a backhand return into the net.
Tsonga missed three break chances in the opening game of the fourth set but converted the fourth after Lajovic made two consecutive unforced errors — a double fault and a forehand in the net. The Frenchman then held to love and broke again as Lajovic showed signs of fatigue following his five-set win over Lucas Pouille on Friday. Tsonga then served out the match.