Gilberto Ramirez promised that Roamer Alexis Angulo would be the first to taste defeat - when the two undefeated fighters collided in Oklahoma on Saturday night.

Ramirez unanimously outpointed Angulo to retain the WBO super middleweight championship, winning 120-108 on one judge's card and 119-109 on the other two.

Making his fourth title defense, the undefeated Ramirez outlasted Angulo in a fairly even 12-round bout in which neither boxer appeared to have the upper hand, and neither landed many significant punches.

Angulo tagged Ramirez early on, and the Mexican fighter decides to box instead of slug it out - which made some of the ringside fans frustrated during the contest.

"He was a tough fighter, it was a tough fight for me and I learned a lot," Ramirez said. "I am really happy because I keep my belt and stay undefeated too, and he has a loss now, like I promised in the press conference —- he had no losses but he does now."

The 27-year-old Ramirez, from Mexico, improved to 38-0. He landed powerful punches in the fifth and eighth rounds.

The 34-year-old Angulo, from Colombia, fell to 23-1.

Angulo had flurries of punches in both the seventh and the 11th rounds, but neither fighter ever appeared to hurt the other. Ramirez sustained a cut under his left eye in the fifth, but his corner attended to it after the round and it never bled again.

"He was an undefeated fighter. He came with a lot of hunger to try to take away my world title. I'm not happy with my performance, but I got the job done. I'm still a world champion. I want to go back to the gym to start training and evolve as a fighter. I want to unify titles and I want to be one of the top pound for pound fighters in the world," Ramirez said.