Yokoi made his debut for the organization on November 24, 2002 at Pride 23 against Dutch kickboxer Jerrel Venetiaan, winning in the third round via armbar submission.
Yokoi performed unexpectedly well,[1] taking Nogueira down repeatedly with judo throws and pulling out reversals and occasional ground and pound on the Brazilian jiu-jitsu expert, but he ultimately fell to an anaconda choke in the second round for the first loss of his career.
Yokoi showed himself active again, gaining dominant position with an early omoplata sweep, but Jackson used his superior strength to reverse him and threw heavy punches and kicks until the referee stopped the match.
He started teaming up with other shoot-style wrestlers, namely Wataru Sakata, Yuki Ishikawa and Yoshiaki Fujiwara, and also enjoyed significant wins in the Fire Festival, beating Kohei Sato and Tetsuhiro Kuroda.
Sato and Yokoi put their eyes in the All Asia Tag Team Championship, taking part in a special league for the vacated title.