Europe took a 3-1 lead on the first day of the Laver Cup despite Rafael Nadal losing in his doubles encounter.
Nadal and Tomas Berdych were beaten 6-3 6-7 (7-9) 10-7 by the World team pairing of Nick Kyrgios and Jack Sock, who prevailed on match tie-break in Prague.
But Europe captain Bjorn Bjorg saw his team dominate the opening day of the inaugural exhibition tournament, with victory in all three singles rubbers over the John McEnroe-led World team even though Roger Federer did not feature amid talk of him playing doubles with Nadal.
Marin Cilic won two tie-breaks in a 7-6 (7-3) 7-6 (7-0) success against Frances Tiafoe.
Dominic Thiem lost an epic first-set tie-break with the big-serving John Isner, but recovered from squandering set points to win the second in a breaker.
He then fought back from 4-0 down in the match tie-break, the Austrian securing a 6-7 (15-17) 7-6 (7-2) 10-7 victory.
Continuing the theme of the day, the match between young stars Alexander Zverev and Denis Shapovalov was decided by two tie-breaks.
After losing the first set, Shapovalov saved four match points in the second only to eventually succumb to Zverev in the shoot-out, the German sealing a 7-6 (7-3) 7-6 (7-5) success.
Victories in Saturday's matches will be worth two points, and Sunday's contests will reward three points for prevailing.