On April 28, 2006, Brock Lesnar appeared inside the ring after the final match of K-1 Hero's Las Vegas and has since signed a deal with the K-1/Hero's. He is currently training with Miletich Fighting Systems under UFC legend Pat Miletich. Brock Lesnar announced on 12 August 2006 in Las Vegas that he has joined the K-1 promotion and will have his first Mixed martial arts match in 2007. Royce Gracie then announced that he will serve as Lesnar's trainer.
From wikipeida.com
Besides you can find a few videos of him related to this topic
His first fight will be on June 2, 2007 against Choi Hong-man of Korea. [5] Royce Gracie then announced that he will serve as Lesnar's trainer
source:Wikipedia.org