SAN JACINTO, Calif., June 12 -- It wasn't the evening's "main event." A week and a half earlier it wasn't even scheduled. But none of that mattered to young Diego Sanchez. Stepping in for John Alessio, who quietly relieved himself of his King of the Cage welterweight belt just days ago, Sanchez dominated Brazilian George Santiago for three rounds Saturday night to win a unanimous decision, becoming the latest in a long line of KOTC 170-pound titleholders.

"I felt like I was in total control of the whole fight," said Sanchez, now 12-0-0. Save a well-executed Santiago second-round takedown, Sanchez delivered a steady and effective stream of ground-and-pound throughout the 15-minute contest.

He was aggressive early. Showing little regard for Santiago's Brazilian jiu-jitsu game, worked on in the Florida gyms of the American Top Team, Sanchez pushed forward, swinging wild, forceful punches. In the clinch, the Albuquerque, New Mexico-native was superior, winning the takedown battle numerous times.

Round two was Santiago's best -- he moved well, scoring with kicks to the inside and outside of Sanchez' lead right leg before landing the heavy takedown -- but his effort was not enough to win the period.

After a stalemate on the ground, referee Cecil Peoples stood both fighters. When Greg Jackson, Sanchez' corner and trainer, implored his fighter to get off first, he listened. Santiago tried to reciprocate, but a wild kick aimed at Sanchez' head only helped the American wrestler dump the Brazilian to his back.

From there Sanchez fired away, scoring with heavy-handed blows reminiscent of something Matt Hughes or Sean Sherk might bring into the ring.

The final period played out like the last minute of round two: a hyper-aggressive Sanchez taking apart a struggling Santiago. Sanchez has been pegged -- with his size, athleticism, competitive nature and anger in the ring -- as a welterweight to watch out for; Saturday night, he showed why.

"I knew that my heart was strong," said Sanchez. "I knew that I was going to overcome. This is my destiny. ... I'm undefeated for a reason. They call me 'Nightmare' for a reason. I got in there and I pounded him."