Rafael Nadal lost for only the second time since July, with David Goffin producing a 6-4, 7-6 (3) win for Belgium to take the ATP Cup quarterfinal to a deciding doubles match against Spain.
The top-ranked Nadal didn't drop a set in three group-stage singles matches in Perth in the new international team competition, but was unable to break down a free-swinging Goffin in Sydney.
The winner of the doubles match later Friday will advance to the semifinals against Australia.
Second-ranked Novak Djokovic guided Serbia into the semifinals with a comeback 4-6, 6-1, 7-6 (4 ) win over Denis Shapovalov of Canada. Serbia will play Russia in the semifinals.
Roberto Bautista Agut had given Spain a 1-0 lead when he continued his run of straight-set wins a 6-1, 6-4 victory over Kimmer Coppejans, a late replacement for Belgium playing captain Steve Darcis.
Nadal went into the second singles match as the favorite, having lost only match — to Alexander Zverev in the round-robin stage of the ATP Finals — since his Wimbledon semifinal loss to Roger Federer.
The 11th-ranked Goffin took it to Nadal, attacking at every opportunity and shutting down his rival's options. He got a break in the fifth game on a rare double-fault from the Spaniard. Nadal broke back immediately and then had five break points in the eighth game but couldn't convert any.
Goffin had four break points in the ninth game and eventually converted, then served out the set.
The second set lasted 82 minutes and contained two service breaks, with Goffin under intense pressure serving second to stay in the set.
Just as Nadal appeared to be getting on top, though, Goffin rallied and dominated the tiebreaker, clinching it with an ace on his second match point.
Djokovic lost a set for the first time in the tournament, but managed to hold off Shapovalov, controlling the tiebreaker after three sets lasting 2 1/2 hours.
Dusan Lajovic had earlier beaten Felix Auger-Aliassime 6-4, 6-2 and so Djokovic's win sealed the victory ahead of the doubles match, giving Serbia a spot in the semifinals. Serbia won the doubles to complete a 3-0 sweep.
“That was so close, it could have gone in a different way easily. (Shapovalov) was playing terrific tennis,” Djokovic said. “It felt, not a little bit, fully like I'm playing at home.”
Djokovic, who has won a record seven Australian Open men's singles titles, went 3-0 in the group stage in Brisbane.
“I'm mean, Brisbane we had amazing support — but this has taken it to a different level,” Djokovic said. "All the Serbian people came out today.
“They were engaged sometimes a little bit too much, and Denis was rightfully annoyed at times, you know, with the sounds, but it was a Davis Cup-like atmosphere, really. I mean, ATP Cup brings this kind of opportunity for players to experience something they don't experience in 90% of the tournaments.”
The temperature topped topped 33 degrees Celsius (91 degrees F) during the match, and it was hazy outside with a lack of breeze, making the conditions inside the arena stifling.
The constant chants and even a burst of trumpet from the flag-waving Serbian fans certainly helped Djokovic, he said. The 16-time major champion reveled in the team environment, with his teammates and coaches on the side of the court, and the echo of “Nole, Nole, Nole” going around the stadium.
Shapovalov complained about the noise made as he served a double-fault to fall behind 4-0 in the tiebreaker, and the umpire asked the crowd to keep quiet during the service motion.
He was agitated during the match but didn't complain later, saying he was getting more comfortable taking on Djokovic and the other top players.
“With my confidence right now, with my game, I really feel that I can take it to anyone, and I feel like against anyone I have a chance to win,” Shapovalov said. “Today again, it's another step for me, showing me that I'm right there with these guys. Honestly, I was a couple points away from taking the match. So, yeah, I think I'm at a really good position."