Perspective | Novak Djokovic isn’t Federer or Nadal. Don’t heckle him. He’s still one of the greats.
![Perspective | Novak Djokovic isn’t Federer or Nadal. Don’t heckle him. He’s still one of the greats.](https://img.washingtonpost.com/rw/2010-2019/WashingtonPost/2019/08/31/Production/Daily/Sports/Images/US_Open_Tennis_24303-122b8.jpg)
NEW YORK — Novak Djokovic has to be the most underappreciated great athlete on Earth, and Earth should do better. Earth can be so amiss, maybe even more than other planets.<p>Djokovic just whooshed into the U.S. Open’s fourth round Friday night, yet it came with familiar reminders that the tenor of a …