Ultimate! Invisible Serve
Having all his moves sealed, Ryoma can only use his "Cyclone Smash". However, having used it repeatedly while enduring Sanada's serves caused him to tire out and his eyes to hurt, so he continued the match with his eyes closed. Pushed by the need to fight for Yukimura (Rikkaidai’s captain), Sanada uses his “Invisible Serve”, a move that effectively hides his swing and the path of the ball.
Aired 31/03/2004EP 127 - Ultimate! Invisible Serve
The Prince of Tennis
Echizen Ryoma is a young tennis prodigy who has won 4 consecutive tennis championships but who constantly lies in the shadow of his father, a former pro tennis player. He joins the Seishun Gakuen junior highschool, one of the best tennis schools in Japan, and there along with his teamates he learns to find his own type of tennis in an attempt to defeat his biggest obstacle of all: his father as well as himself.
(Source: Anime News Network)