Roger Federer and Rafael Nadal have competed against each other on the tennis court many times, but on Friday they were seen competing to get into the ear of Fabio Fognini - who was playing for Team Europe against Team World in the Laver Cup.
"We need to make sure our rankings are high enough to play together. Wherever we can play together, we are still trying to. The good part is that the ranking deadline for the Olympics is the 2020 French Open," said Rohan Bopanna.
Serena Williams suffered her fourth consecutive defeat in a Grand Slam final at the U.S. Open earlier this month, as she again came agonisingly close to Australian Margaret Court's all-time record of 24 majors before falling in straight sets.
Roger Federer won doubles gold with Stan Wawrinka at the 2008 Beijing Olympics and silver in singles at the 2012 London Olympics at Wimbledon. He missed the 2016 Rio de Janeiro Olympics because of injury.
Former world number one Murray has played only a handful of singles matches since having a career-saving hip surgery earlier this year but qualified for the nation-based tournament with a protected ranking.