Roger Federer and Rafael Nadal played as doubles partners for the first time on the second day of the inaugural Laver Cup in Prague.
Swiss Federer and Spaniard Nadal, who have won a combined 35 Grand Slam titles, are part of a Europe side playing a World team over three days.
They beat Americans Sam Querrey and Jack Sock 6-4 1-6 10-5 to give Team Europe a 9-3 lead.
The winner is the first to 13 points, with 12 points available on Sunday.
“We will always be rivals as long as we are active. And after this we will be rivals again,” said Federer. “But this was something very special. Knowing you can trust him in the big moments, seeing his decision-making, seeing his thought process, it was very interesting.”
Nadal called the experience “unforgettable” adding: “To have the possibility to have Roger next to me is a huge privilege… something I wanted to make happen at some point and today I made it happen.”
Team Europe’s players include world number four Alexander Zverev and seventh-ranked Dominic Thiem, while Nick Kyrgios and Denis Shapovalov, who impressed at the US Open, have represented Team World.
None of the matches played are part of the ATP Tour but they have attracted healthy crowds in the Czech capital.