Lionel Messi and Cristiano Ronaldo are two of the greatest soccer players to ever play the beautiful game and have dominated the sports in the last 15 years winning 11 Ballon d'Or between them and with age gradually catching up on the two, Messi is 34, Ronaldo is 36 and are nearing their retirement.
Roger Federer is one of the greatest tennis players of all time. He has won 20 Grand Slam titles and was world number one for over 200 days, a record later broken Novak Djokovic. He has been on and off the court since 2020 due to injuries and at the age of 40, he's also nearing his retirement.
Roger Federer looks more likely to be the one to retire first among the three sports great because at the age of 40, and multiple injuries that has forced him to miss many tournament, his time could he up very soon as he make way for the new guys. His close friend Rafael Nadal could also follow suit.
The battle of who retires last will be between Lionel Messi and Cristiano Ronaldo. The two players recently signed two years contract, Messi with PSG and Cristiano Ronaldo with Manchester United. Both players are expected to play a few more seasons afterwards but would certainly retire after Roger Federer.