If you have read Giri Nathan's tennis blogs on Defector, you know that no one else writes about that sport with the insight, invention, and humor that he does. If you have just read Defector this week, you'll know that he has a new book out called Changeover that enfolds some of the reporting and writing he's done here and a bunch of new stuff to tell the story of the rising rivalry between Carlos Alcaraz and Jannik Sinner.