Although there were no official titles at stake at the MGM Grand, both fighters had confirmed their status as 9st champions in recent bouts.

Barrera had refused to accept the lightly-regarded IBO title when inflicting a first defeat on Naseem Hamed and also cast aside the WBC crown when edging old rival Erik Morales.

Tapia, meanwhile, gave up the IBF belt he earned for beating Manuel Medina in order to take on Barrera. Barrera dominated the contest throughout before getting the decision by scores of 116-112 and 118-110 twice.

Barrera looked much the sharper early on and was able to pick Tapia off at will in the opening rounds.

Tapia charged forward in his customary fashion but was constantly forced to eat up Barrera's textbook jabs.

Barrera was finally forced to take refuge on the ropes in round six and Tapia, despite suffering a bloodied nose, enjoyed his share of the action in the seventh.

Amazingly, both fighters touched gloves and saluted each other after a hard-fought ninth.

Barrera improved his record to 56-3 while Tapia suffered the third defeat of his colourful 57-fight career.

"My corner told me to go out there and jab and control the fight," Barrera said through an interpreter.

"We didn't want any accidents to happen."

Tapia accepted he had been second best.

"I fought the king of the featherweights," said Tapia. "I couldn't catch him. I did the best I can, and I'm still here."

Barrera now has his sights set on next week's bout between Morales and Paulie Ayala.