He is best known for being the coach and mentor to multiple MMA world champions, most famously Khabib Nurmagomedov, Islam Makhachev, Luke Rockhold, Frank Shamrock, Daniel Cormier, and Cain Velasquez.

From there, he went to West Coast Tae Kwon Do and trained under Scott Coker (former CEO of Strikeforce and current president of Bellator MMA).

In 1995, Mendez defeated Conrad Pla (founder of Tristar Gym) via split decision to win the vacant ISKA Light Heavyweight Championship.

That exposure led other fighters like to seek out Mendez as he rode the wave of MMA's growing popularity.

Penn joined AKA in 2001 in preparation of his MMA career debut and would eventually become UFC champion in both the Lightweight and Welterweight divisions.