Novak Djokovic is 38 and trying to conquer a younger man's game as he heads into the U.S. Open semifinals on Friday. It's been two years since his most recent Grand Slam title, which — to him — must feel like an eternity.
Last season was his first without earning at least one since 2017. And Djokovic is clear that, at this point in his career, those big trophies from the sport's four biggest events are all he really cares about.
