Paris - Australia's hopes of reaching the Davis Cup final for the first time in 14 years suffered an early setback on Friday when world No 185 John Millman went down 6-7 (4/7), 6-4, 6-3, 7-5 to Belgium's David Goffin in the opening rubber of the semi-final.
Australia, the 28-time champions, haven't made the championship match since they downed Spain in the 2003 final in Melbourne.
World No 12 Goffin predictably edged the first point of the semi-final, being played on clay in Brussels, despite suffering an early wobble.
"I had to dig deep. It would not have been possible without the support of the fans," said Goffin.
Australia will try to level the tie later on Friday when world No 20 Nick Kyrgios, who lost to Millman in the first round at the US Open, faces tricky 77th-ranked Steve Darcis.
Kyrgios, who has been carrying a hip injury, goes into the match claiming: "I am not the professional tennis needs me to be".
Writing on www.playersvoice.com, Kyrgios said he yearns to lead a "normal life".
"I'm not making the improvements I should because I don't want it enough, I'm not taking it seriously enough," he said.
"I know that and there's no point trying to convince anyone otherwise.
"There is a constant tug-of-war between the competitor within me wanting to win, win, win and the human in me wanting to live a normal life with my family away from the public glare."
Belgium are attempting to reach their second Davis Cup final in three seasons having lost to Great Britain in 2015.
In Lille, Dusan Lajovic made a mockery of the absence of Novak Djokovic to give Serbia a shock 1-0 lead over France in their semi-final.
World No 80 Lajovic edged Lucas Pouille, ranked 58 places higher, 6-1, 3-6, 7-6 (9/7), 7-6 (7/5) in the first rubber of the tie also being played on clay.
"This is what the Davis Cup is all about," said Serbia captain Nenad Zimonjic, who is without his three leading singles players - Djokovic, who is sidelined until 2018 with a wrist injury, Janko Tipsarevic and Viktor Troicki.
"The third set was the key. Whoever was going to win that one was going to turn it all around. We need a miracle but we believe in our players."
Lajovic took victory on a fifth match point.
France, the nine-time champions, will look to national number one Jo-Wilfried Tsonga to level the semi-final when he faces Davis Cup debutant Laslo Djere, the world No 95.
Davis Cup semi-final results on Friday (all times GMT):
At Lille (clay court, outdoor)
France 1 Serbia 1
Dusan Lajovic (SRB) bt Lucas Pouille (FRA) 6-1, 3-6, 7-6 (9/7), 7-6 (7/5)
Jo-Wilfried Tsonga (FRA) bt Laslo Djere (SRB) 7-6 (7/2), 6-3, 6-3
Saturday (from 12:00)
Nicolas Mahut/Pierre-Hugues Herbert (FRA) v Nenad Zimonjic/Filip Krajinovic (SRB)
Sunday (from 11:00)
Jo-Wilfried Tsonga (FRA) v Dusan Lajovic (SRB)
Lucas Pouille (FRA) v Laslo Djere (SRB)
At Brussels (clay court, indoor)
Belgium 1 Australia 0
David Goffin (BEL) bt John Millman (AUS) 6-7 (4/7), 6-4, 6-3, 7-5
Steve Darcis (BEL) v Nick Kyrgios (AUS)
Saturday (from 13:00)
Arthur De Greef/Ruben Bemelmans (BEL) v Jordan Thompson/John Peers (AUS)
Sunday (from 12:00)
David Goffin (BEL) v Nick Kyrgios (AUS)
Steve Darcis (BEL) v John Millman (AUS)