The Underarm Serve Trick Shouldn't Only Be Used By Nick Kyrgios
by Giri Nathan from Deadspin > Sports News Without Fear, Favor or Compromise on (#4BT9A)

The serve remains the biggest offensive weapon in the game of tennis. If a player can't find a way to solve a dangerous server, they'll struggle to find any traction in a match. So that returner has to find a counter of some kind.