"Lleyton and I have put so much dedication into this, the Davis Cup has been my No.1 priority this year", Kyrgios said, referring to Australia captain Lleyton Hewitt.
Victory for Nick Kyrgios or John Millman in either Sunday's singles rubber will be enough to secure a decider on home soil against Serbia or France in November.
That's followed by French No 1 Jo-Wilfried Tsonga crossing swords with Davis Cup debutant Laslo Djere, the highest-rated Serbian at No.80 in the world.
France is bidding for a first Davis Cup title since 2001, having lost three finals since with the most recent a defeat by Roger Federer's Switzerland in 2014.
Mahut had been battling a calf injury, and thanked the medical staff for getting him ready to play.
Noah's team are favoured to progress to the final against a Serbian side sorely missing injured former World No 1 and 12-time Grand Slam victor Novak Djokovic, Viktor Troicki and Janko Tipsarevic.
Meanwhile in Brussels, Australia also need just one more point to reach the final for the first time since they won the title in 2003 after John Peers and Jordan Thompson breezed past Arthur de Greef and Ruben Bemelmans of Belgium 6-3 6-4 6-0.
In Lille, the 22nd-ranked Pouille dropped his serve immediately and looked nervous throughout the first set wrapped up by Lajovic in 25 minutes. "It's always important in Davis Cup".
Mahut and Herbert broke at love to open the final set and it seemed that the match will not last for too long when they earned another break in game 7, moving 5-2 in front and serving for the win.
"It would have been extremely hard to play five sets", Lajovic said.
The big-serving star won 7-6 6-3 6-3 and it is the French who will take an advantage into Sunday's reverse singles after Pierre-Hugues Herbert and Nicolas Mahut beat Filip Krajinovic and Nenad Zimonjic 6-1 6-2 7-6 in the doubles.