Analysis: At 20-19-16, Federer vs. Nadal vs. Djokovic is fun

Rafael Nadal, of Spain, holds up the trophy after defeating Daniil Medvedev, of Russia, to win the men's singles final of the U.S. Open tennis championships Sunday, Sept. 8, 2019, in New York. (AP Photo/Adam Hunger)

NEW YORK — At some point, of course, Rafael Nadal and the rest of the Big Three will stop winning Grand Slam titles, someone younger will emerge and a shift at the top of tennis will happen.