Lille: David Goffin never once lost his cool as he beat a nervy Jo-Wilfried Tsonga 7-6(5) 6-3 6-2 to put Belgium level at 2-2 with hosts France, sending the Davis Cup final into a decisive fifth match on Sunday.
The world number seven saved six break points in a thrilling opening set of the first reverse singles, before cantering to victory in a packed Pierre Mauroy stadium.
The final encounter was set to feature local favourite Lucas Pouille against Steve Darcis, who has never lost in five decisive Davis Cup matches.
France, who have not lifted the trophy since 2001, are looking to clinch their 10th title while Belgium are seeking their maiden Davis Cup.
Tsonga had won his first singles against Darcis after Goffin, high on self-confidence since he finished runner-up at the ATP Finals, had put Belgium ahead by beating Pouille on Friday.
Richard Gasquet and Pierre-Hugues Herbert defeated Ruben Bemelmans and Joris De Loore on Saturday to give Les Bleus a 2-1 advantage.
Tsonga hoped to become a national hero on Sunday but instead lost his composure in a bitter end to the match after a disputed call in the third set, triggering huge boos from the 27,000 crowd.
The match was already long lost for the world number 15, who was simply beaten by a much better player on the indoor hardcourt.