Team Europe saw their lead sliced to 7-5 going into the final day of the Laver Cup after Nick Kyrgios and Jack Sock beat Rafa Nadal and Stefanos Tsitsipas in the doubles.
Kyrgios was inspired in the match tiebreaker as Team World came through 6-4 3-6 10-6, easing the pain of an otherwise difficult day that saw the Aussie lose to Roger Federer and Nadal beat Milos Raonic in singles.
The World pair took the first set but Nadal and Tsitsipas fought back to level in the second and final set, forcing the match to go to a match tiebreaker.
But Sock and Kyrgios reasserted their superiority and reduced Europe's points advantage going into Sunday.
Earlier, Nadal defeated Raonic 6-3 7-6(1) and Federer maintained his 100% Laver Cup record against Kyrgios with a thrilling 6-7(5) 7-5 10-7 victory.
Nadal, who had helped Federer to victory over Kyrgios with some tactical pointers, was made to work hard by Raonic but he played the bigger points much better.
Playing in front of 17,000 fans in Geneva, home favourite Federer beat Kyrgios for the third time in as many editions of the competition to take Europe closer to the 13-point victory target ahead of the night session that features Rafa Nadal.
"It was really close that first set so it was tough to lose," 20-times Grand Slam winner Federer said.
"The crowd could feel it, I could feel it. I needed to get some energy going but you can't do that if you don't play any good shots and Nick was playing very well. I was just trying to stay focused. If you can turn the momentum, the crowd gets back into it and I need some earplugs next time, it was just phenomenal."
Federer also said that advice from fellow European Nadal had helped him find his way to victory at 4-5 down in the second set.
With the match evenly poised, Federer was struggling to dominate the rallies against his younger opponent, at which point Nadal stepped up and told the Swiss to keep the points short when he was serving.
Nadal explained: "After five shots, you are winning more [points]. I know it's tough because he reads the ball so well... Wait for the right one and then attack because he's not missing."
The advice brought instant rewards as two unforced errors from Kyrgios allowed Federer to break from 5-5, before another tip from Nadal gave him another advantage.
Nadal told Federer to use spin on his serve and to keep the ball higher in play, helping Federer hold serve and take the match to a deciding tie-break, where he was able to emerge victorious.