Paris - Davis Cup rookie Benoit Paire helped holders France to a 2-0 semi-final lead over Spain with Croatia in command against the United States by the same margin after Friday's opening singles.
France captain Yannick Noah had admitted that handing Paire a Davis Cup debut in a semi-final was "not an easy choice" but the gamble paid off handsomely.
The bearded 29-year-old enjoyed what he termed "a dream" 7-5, 6-1, 6-0 defeat of Pablo Carreno Busta to get Noah's defending champions off to a perfect start in less than two hours.
"I've waited a long time for this," smiled Paire, the world No 54 who showed no signs of the hot-headed streak that cost him a $16,500 fine for an epic three-smashed-racket meltdown in Washington last month.
"I never had the choice before now and though it's been a long time, hopefully it's not too late for me and I'll get more chances."
If Paire's win was straightforward, Lucas Pouille's nerve jangling five set victory over Roberto Bautista-Agut in the following match was anything but.
The French No 1 fought back from losing the first set to win 3-6, 7-6, 6-4, 2-6, 6-4 and leave France one point away from a date in the final in November.
Pouille took to the court at Lille's Stade Pierre-Mauroy after an indifferent build-up and he struggled to find consistency, his play ranging from the sublime to the not so sublime.
His 87 unforced errors only complicated his task but he never relented and his persistency prevailed.
He recovered well from losing the first set to level on the tiebreak. Then followed his best form to go 2-1 up, only to let his Spanish rival back in the game in the fourth.
Breaking at 5-4 in the finale he still required three match points to put France's second point up on the board, to the delight of the home fans after a classic three hours and 41 minutes of Davis Cup action.
"I thought Luca deserved it, but it was so close," said Noah.
"At this level, in a semi-final, it's all about who goes for it. You can't wait for the mistake."
Spain turned up in Lille without Rafael Nadal. The 17-time Grand Slam champion has helped Spain capture the annual trophy four times, in 2004, 2008, 2009 and 2011, but was ruled out with a knee injury
France are on the brink of their second successive final, with Saturday's doubles pairing of Julien Benneteau and Nicolas Mahut now in the position of clinching the decisive win against Marcel Granollers and Feliciano Lopez.
As Pouille was starting his match Croatia had already notched up their commanding 2-0 lead over the United Status in the other semi-final in Zadar.
In the first rubber Borna Coric, world No 18, justified his favourite's tag and defeated Steve Johnson 6-4, 7-6 (7/4), 6-3.
Croatia's top player and world No 6 Marin Cilic then defeated Frances Tiafoe, a Davis Cup dbutant 6-1, 6-3, 7-6 (7/5).
Croatia could clinch their final ticket in Saturday's doubles in which Ivan Dodig and Mate Pavic will face Mike Bryan and Ryan Harrison.
Croatia have made the final twice, in 2005, when they were crowned champions, and 2016.
Jim Courier's team is missing two top players - John Isner, world No 10 who has stayed home due to family reasons, and injured Jack Sock.