Laver Cup: Roger Federer and Alexander Zverev win doubles as Team Europe lead 3-1
Roger Federer and Alexander Zverev won their Laver Cup doubles match as Team Europe lead Team World 3-1 after day one of the event in Geneva, Switzerland.
Federer and Zverev beat Jack Sock and Denis Shapovalov 6-3 7-5.
Shapovalov also lost to Dominic Thiem while Greece's Stefanos Tsitsipas beat American Taylor Fritz.
Sock had earlier beaten Fabio Fognini of Italy 6-1 7-6 to secure Team World's only point of the opening day.
Shapovalov and Sock converted just one of 16 break points, failing to take any of six set points in one game off Zverev's serve during the crucial second set.
After Zverev held serve to level the set at 5-5, a double fault from Shapovalov in the next game gave the Team Europe pair a crucial break.
Federer served out the next game to secure victory and move further ahead in the all-time Laver Cup standings with 13 points.
Speaking in front of his home crowd, Swiss world number three Federer said: "All of us tennis players travel around the world for 10, 11 months of the year.
"There's no place like playing at home, so this is a very special night for me."
Austrian world number five Thiem saved three match points against Canada's Shapovalov in the opening singles match of the competition before going on to win 6-4 5-7 13-11 courtesy of a super tie-break.
Tsitsipas also needed a super tie-break to overcome fellow tournament debutant Fritz 6-2 1-6 10-7.
That put Europe back in front after American Sock became the first Team World player ever to win an opening-day singles match with victory over Fognini.
Two points per match are on offer on day two of the three-day tournament, with the first team to reach 13 points declared the winner.
The Laver Cup is into its third year but this is the first time the tournament is an officially sanctioned ATP Tour event.
The previous tournaments, in Prague and Chicago, took place on an exhibition basis.