Team Europe retained the Laver Cup as Alexander Zverev fought back to beat Kevin Anderson to push Bjorn Borg's side over the 13-point line.
After securing the inaugural title in Prague last year, the Europeans took two straight singles matches in Chicago to seal the title.
Going into the final day at 7-5 in favour of Europe, Team World retook the lead through John Isner and Jack Sock who saved two match points and saw off Roger Federer and Zverev 4-6 7-6 (7/2) 11-9.
But Federer put Europe on the brink of victory with a three-set win over Isner 6-7 (5/7) 7-6 (8/6) 10-7 and Zverev did the honours against Anderson.
The world number nine took the first set on a tiebreak 7/3, but the German had a break in the second to take it 7-5.
He then went on to win five points in a row to take the final set 10-7 as Europe took an unassailable lead.
Speaking after the win, Zverev said: "It was such a close match all around... not just this one, the whole weekend. A few points here or there could have changed the whole thing."
Team World captain John McEnroe said: "This team, I am so proud of these guys, it is awesome to be a captain for Team World. We have got great camaraderie and dammit, we're going to win this one next year."
Debutant Kyle Edmund won his only game on Friday against Jack Sock, while fellow first-timers Grigor Dimitrov and David Goffin won their singles matches on Friday but lost as a doubles pair to Nick Kyrgios and Jack Sock on Saturday.
Novak Djokovic, the current world number three, would have faced Kyrgios in the final singles tie after two straight defeats at the United Center - once with Federer as a pair against Anderson and Sock and again to Anderson on Saturday in the singles.
