Amir Khan will fight at middleweight for the first time when he takes on Canelo Alvarez at a catchweight 15lbs

The WBC has defended Canelo Alvarez's catchweight contest with Amir Khan after criticism from Gennady Golovkin's trainer.

Khan made his name at lightweight and is moving into uncharted territory to fight for Alvarez's middleweight belt on May 7, but the WBC has sanctioned a 155lbs limit - five pounds under the statutory maximum.

Unbeaten IBF and WBA champion Golovkin is mandatory challenger for the WBC title, but there have been repeated warnings from his team that he will not surrender a natural size advantage by fighting at a compromise weight.

That point was last week reinforced by trainer Abel Sanchez, who said "'GGG' will not bow to diva demands and will fight at 160."

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But WBC boss Mauricio Sulaiman says the Canelo-Khan agreement is within the rules and will produce "a sensational fight".

He told World Boxing News: "The fight is for the WBC middleweight championship and if there is any weight agreement, such is a private contract between the fighters.

Gennady Golovkin's trainer has warned he will not drop below 160lbs for Alvarez

"The division limit is 160, so any weight lower than that is considered as official and within the rules.

"Canelo versus Khan is a sensational fight. Amir Khan has tremendous ability, speed, ring generalship and vast experience in major fights, whilst Canelo is coming from his biggest fight in defeating Miguel Cotto last November."