"Legacy is really important": Federer makes surprise Laver Cup appearance 

Roger Federer may be injured, but that didn't stop the 20-time major champion from jumping on a plane to attend this year's Laver Cup. Federer was joined by Laver Cup chairman, Tony Godsick and Team World's head coach John McEnroe for an exclusive on-court interview for CNBC.

Federer touched on how the special event came to fruition, and the importance of celebrating the sport's all-time greatest and their legacies.

"For me the legacy is really important, and that we remember it in tennis because we have a really rich history," Federer said during the live interview. "Rod Laver, of course was a hero to a lot of us especially Bjorn Borg and also to John (McEnroe) to me he was that big legend that was able to win two times the calendar Grand Slam.

"He was also the one that went from amateur to professional sports and that's where the idea came in with Tony (Godsick) and I on a ride in Shanghai that we could do something for the legacy of the game. And, incorporate all the young ones coming through and learning from the best like John and Bjorn."

During Friday's opening match, Federer received a standing ovation. He mentioned he wouldn't be attending this year's event due to his knee injury and recovery process, but he had tennis fans fooled.

That car ride between Federer and Godsick turned into reality, as the Laver Cup's fourth edition is already underway. Team Europe has yet to fall to Team World and has claimed the crown in all three previous editions. This year, Europe is well on their way to another successful event, as they've taken a solid 2-0 lead heading into the Day 1 night session.

Team Europe's Casper Ruud defeated Team World's Reilly Opelka, and Matteo Berrettini squeezed past Felix Auger-Aliassime in a nail-biting battle.