Britain's Cameron Norrie lost on his Laver Cup debut as Taylor Fritz beat him to pull Team World level with Team Europe after day two's opening session.
Matteo Berrettini had put Europe into a 4-2 lead with a 7-6 (11-9) 4-6 10-7 win over Felix Auger-Aliassime.
Roger Federer, who finished the final match of his career in the early hours of Saturday, was on the bench to support Norrie and Berrettini.
Federer was also coaching the Italian world number 15 - which Berrettini described as surreal because the Swiss great had inspired him to become a professional tennis player.