Preparing to serve, the one player collects three balls in his left hand or on his racket. After throwing one away, he sometimes gets another. Once he's chosen two, he looks closely at them before putting one in his pocket. Before the first serve, he bounches the ball with his racket and then few times with his left hand. — Preparing to serve, the other player collects four balls in his left hand or on his racket. He throws one away quickly, then looks closely at the remaining three before tossing one away and pocketing a second. Before the first serve, he bounces the ball a few times with his left hand. (Andrew Shields, #111Words, 13 July 2025)

How two tennis players prepare to serve