In the world of mixed martial arts (MMA), Roach has trained former UFC heavyweight champion Andrei Arlovski and was one of his primary trainers for Arlovski's victory over Ben Rothwell on July 19 at Affliction's inaugural show. He has also trained MMA fighter Dan Hardy for his fight with Marcus Davis at UFC 99 as well as MMA greats, Tito Ortiz, Anderson Silva, and BJ Penn. In May 2010, he began a training engagement with Georges St-Pierre in advance preparation for the fighter's successful UFC welterweight title defense against Josh Koscheck at UFC 124. Roach has also trained many other prominent mixed martial artists, such as: pro-boxer and kickboxer, and former EliteXC lightweight champion, K.J. Noons, Roger Huerta, and Rameau Thierry Sokoudjou. In March 2010, Roach expressed interest in wanting to train former Pride FC and WAMMA heavyweight champion, Fedor Emelianenko.