发强烈下旋球时摩擦球的底部 初学者及中等水平的选手，发下旋球的意识往往是自上而下用力摩擦球，但对方接发球时直接下网失误并不多，因为这种摩擦球的方法旋转不强。 在高水平比赛中，接发球时明知对方发的是下旋球但还是接下网失误，主要是对方发过来的球比自己想象的要转 Fierce spin down the bottom of the friction ball at the bottom of beginners and mid-level players, the spin down the consciousness is often friction from top to bottom friction ball, but the other side when receiving the ball is not directly under the network error, because this Friction ball method is not strong rotation. In the high level of competition, the service made known to each other is spin down the ball but still under the net mistakes, mainly from the other side than the ball to their imagination