The biggest question for both Yannick Noah, the French skipper, and his Belgian counterpart, Johan van Herck, is the doubles pairing.
In the singles on Friday, Noah will no doubt open with Jo-Wilfried Tsonga (ranked number 15 in the world) and Lucas Pouille (18). Richard Gasquet (31) seems too far behind to risk.
In the doubles, Noah has generally preferred the specialist pairing of Nicolas Mahut and Pierre-Hugues Herbert, who won the 2015 US Open and the 2016 Wimbledon doubles together. But "P2H" has a back injury which caused the pair to forfeit their last group match at ATP Finals in London on November 16.
Nevertheless, Julien Benneteau, a former French Open doubles winner who is back to his best at the age of 35, could still rejoin Mahut in the doubles on Saturday. They played together in the quarter-final in April.
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Belgium will be led by seventh-ranked David Goffin, who showed his form by beating Roger Federer to reach the final in London last week.
"France are clearly the favourites because they're playing at home, have won the Davis Cup several times before and have a very consistent team with very good players," Goffin told AFP.
Barring a major surprise, the other Belgian singles player will be Steve Darcis. But who will partner Ruben Bemelmans (118) in the doubles?
Joris de Loore (276) missed the last match against Australia because of a knee operation. Van Herck has named him in the squad but has kept open the option of retaining Arthur de Greef (181).
- Routes to the final -
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The Belgians are trying to win their first Davis Cup title. They reached the final in 2015 but lost to a Britain team containing Andy Murray. They had to work hard to return this time.
Belgium were taken to the third day in all of their matches.
They won 4-1 in Germany in the first round despite resting Goffin, although he returned for the quarter-final victory over an Italy team that was without Fabio Fognini.
In the semi-final, against Australia in Brussels, Belgium entered the last day trailing but Goffin fought back to beat Nick Kyrgios before Darcis beat Jordan Thompson in straight sets to stay perfect when playing last.
Yet that semi-final victory over Serbia, also in Lille, was not without some strange elements which raise questions ahead of the final.
As he won the decisive rubber, Tsonga told Noah not to speak to him during the changeovers. The captain spent the weekend alternating between a strange lassitude, as he slumped in his courtside seat, and intense self-criticism until his attitude was transformed on Sunday by victory.
At the press conference after the match he denied any suggestions of a bad atmosphere within the squad.
He said that Cedric Pioline, a former French Davis Cup player, had "also asked Noah to let him have some quiet moments".
Noah, who was captain in 1991-92 and 1995-98 says he is "improved" for his third stint, which began in 2015.
Asked whether he would continue, he added another layer of mystery, saying: "I have no certainty about anything.