Strikeforce: Shamrock vs. Gracie was the inaugural mixed martial arts event promoted by Strikeforce. The event took place at the HP Pavilion at San Jose in San Jose, California on March 10, 2006. The main event was the long awaited match between Frank Shamrock, returning to the sport after a 3-year absence, and Cesar Gracie. The show is also notable for featuring the MMA debut of Cung Le. This was the first Strikeforce event.

UFC Fight Night 6: Sanchez vs. Parisyan was a mixed martial arts event held by the Ultimate Fighting Championship on August 17, 2006. The event took place at the Red Rock Resort Spa and Casino in Las Vegas, Nevada.

UFC Fight Night 6.5: Ortiz vs. Shamrock 3 was a mixed martial arts event held by the Ultimate Fighting Championship on October 10, 2006. The event took place at the Seminole Hard Rock Hotel and Casino in Hollywood, Florida and was broadcast live on Spike TV in the United States and Canada. The main event featured the third and final encounter between Tito Ortiz and Ken Shamrock. At UFC 61, the two fighters met for a second time, with Ortiz reigning victorious via technical knockout.