Richard Gasquet has been called into the France team to face Belgium in the Davis Cup final.
France captain Yannick Noah had originally chosen a specialist doubles team of Mahut and Pierre-Hugues Herbert for the tie in Lille, with Jo-Wilfried Tsonga and Lucas Pouille his singles players.
But just prior to Thursday's draw, it was announced that world number 31 Gasquet would come into the line-up in place of Mahut, who suffered a cut to the finger on his racquet hand during last week's ATP Finals in London.
Noah duly nominated Gasquet and Herbert for Saturday's often-crucial rubber but stuck with Tsonga and Pouille for Friday's opening singles matches.
Pouille will open the tie against David Goffin with Tsonga and Belgian number two Steve Darcis following them on to court.
However, Gasquet does provide another option for Sunday's reverse singles if necessary.
Meanwhile, Belgium also made a late change to their four-man team with Joris de Loore coming in for Arthur de Greef. De Loore and Ruben Bemelmans were nominated by captain Johan van Herck for the doubles.
Belgium's hopes rest largely on Goffin, the highest-ranked player involved in the tie. The new world number seven was the runner-up at the ATP Finals, losing Sunday's final to Grigor Dimitrov.
France, seeking a first Davis Cup success since 2001, are 2/7 favourites with Sky Bet, with Belgium offered at 11/4 to win the trophy for the first time in their history.
The tie is being played on an indoor hardcourt in the Stade Pierre Mauroy - Lille's football stadium which has a retractable roof. 27,000 fans will be able to attend each day - one of the largest crowd's in tennis history.
Davis Cup final draw: France v Belgium
Friday (1300 GMT)
Lucas Pouille v David Goffin
Jo-Wilfried Tsonga v Steve Darcis
Saturday (1300 GMT)
Richard Gasquet & Pierre-Hugues Herbert v Ruben Bemelmans & Joris de Loore
Sunday (1230 GMT)
Jo-Wilfried Tsonga v David Goffin
Lucas Pouille v Steve Darcis
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