Amir Khan has revealed his reluctance to insist on a rehydration clause for his May 7 fight with Saul Alvarez owing to his desire to make the biggest possible statement.

Khan will fight above welterweight for the first time at a catchweight of 155lbs, officially middleweight, to challenge Alvarez for the Mexican’s WBC title at Las Vegas’ T-Mobile Arena.

Given the significant difference in size between challenger and champion when they appeared together in London Monday, it appeared a risky oversight that Khan did not demand a restriction on Alvarez’s weight on fight night.

The Mexican’s frame means there is little to stop him gaining a further 20lbs after weighing in to effectively compete at light-heavyweight and therefore leaving Khan, the underdog who turned professional as a lightweight, at an even greater disadvantage.

There is no question Khan’s best chance comes in using his superior speed and mobility against his stronger opponent, so asked why he took such an unnecessary risk, he said: “I want to do everything naturally because when I beat him I want to beat him fair and square. I don’t want people thinking ‘he was dehydrated, he was small, he couldn’t put weight on’.

“Yeah (we considered a clause), I spoke to Virgil (Hunter, my trainer), and Virgil is the one who said to me ‘look, if you’re happy with the fight, it’s a good fight for us’.

“He’s been watching videos (of Alvarez) as well. What I have to do is stick to the gameplan. I can’t make any mistakes because I can get hurt for that.”

Alvarez is in the UK for the first time to promote his date with Khan, and he insists it is not the mismatch some, particularly in the US, have called it. “Amir Khan’s a great fighter, a serious fighter, a serious threat,” he said. “On May 7 this is going to be a great fight.”