Diaz was victorious in DREAM 3, defeating Katsuya Inoue by TKO in the first round. With Strikeforce's acquisition of ProElite's assets, CEO Scott Coker had announced that Nick would face off against MMA legend Frank Shamrock at a Catchweight of 179 lb, at their upcoming event, , in Shamrock's hometown of San Jose on April 11 at the HP Pavilion. Nick was successful in the fight, defeating Shamrock via TKO due to strikes in the second round. Throughout the fight, Diaz was dominant in all areas using effective positioning on the ground, once mounting Frank in the end of the first round, before finally finishing the fight in the second round with a body shot that crumpled Frank to the mat and follow up punches before referee John McCarthy called a halt to the bout. In the interview he stated "It's hard to hate the guy, he's been doing what I've been wanting to do and saying what I've wanted to say for a long time".