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. (thetvdb.com)