Team Europe took a commanding 3-1 lead over Team World in the Laver Cup on Friday, despite seeing their high-profile doubles pairing of Roger Federer and Novak Djokovic suffer the defending champions' only defeat of the first day in Chicago on Friday.
Jack Sock and Kevin Anderson combined to deliver the sole triumph for their side, overcoming the world's second and third ranked singles players 6-7 (5), 6-3 (10-6) to prevent an opening day shutout for Team Europe.
All eyes were fixed on longtime rivals Federer and Djokovic as they took the court for the final match, combining forces to play together for the first time after Team Europe had swept the first three singles matches.
The early chemistry took time to develop for both players, and Djokovic accidentally hit Federer on the back of the head during the third game, but the star-studded duo proved strong enough to claim the first set in a tiebreak.
Sock and Anderson found their rhythm in the second set, blasting five of their eight aces to level the contest, before the pair took advantage of a Federer double fault at 4-4 in the 10-point match tiebreaker and held on for a critical triumph.
Europe had earlier built their advantage on singles victories for Bulgarian Grigor Dimitrov, Briton Kyle Edmund and Belgian David Goffin.
Dimitrov rolled through the opener with a 6-1, 6-4 victory over American Frances Tiafoe before his team mates were required to dig deeper for their wins.
"It's pretty amazing," Dimitrov told reporters, of the team spirit.
"Usually we're always against each other and now, these guys are actually cheering for me. It's a nice feeling and I think it's great for you guys to see that."
Edmund overcame Sock 6-4, 5-7, (10-6) despite struggling with his serve at times and coughing up four double faults, before Goffin staved off a late rally on his way to a 6-4, 4-6, (11-9) triumph over Argentine Diego Schwartzman.
Schwartzman battled back from a 5-1 deficit in the deciding tiebreaker to level at 7-7 before Goffin pulled clear.
"It was an amazing atmosphere," Goffin said.
"I had to stay focused."
Day Two will feature three more singles clashes, including Federer v Nick Kyrgios, and an additional doubles match, with two points on offer for any victory.
Sunday's four matches are worth three points apiece with the first team to reach 13 points crowned champions after Europe claimed last year's inaugural event by a 15-9 margin in Prague.