Kell Brook v Gennady Golovkin: Brook wants to be 'best boxer in world'

Kell Brook believes beating Gennady Golovkin would be the greatest ever victory by a British boxer.

Brook, the IBF welterweight champion, is jumping two weights to challenge for Golovkin's WBC and IBF middleweight titles on Saturday.

The last reigning welterweight world champion to win a middleweight world title was Emile Griffith in 1966.

"This fight will separate me from the rest of Britain's world champions," Brook told BBC Sport.

"Having beaten the best pound-for-pound boxer in the world, that will make me the best pound-for-pound boxer in the world. That excites me so much.

"I can't wait to prove the doubters wrong. This is going to be the best win that any British fighter has ever pulled off."

Many observers believe the match between Brook and unbeaten Kazakhstani Golovkin, who has 32 knockouts from 35 professional fights, is a mismatch.

The WBA, whose middleweight title Golovkin holds, has refused to sanction the fight because it says it is concerned about the Sheffield fighter's health.

Brook will be looking to achieve where compatriot and welterweight rival Amir Khan failed, when the latter jumped two weight classes but was knocked out by Mexico's Canelo Alvarez

But Brook, 30, insists he feels more comfortable at the middleweight limit of 160lb, rather than the welterweight limit of 147lb.

Indeed, Brook has been heavier than Golovkin at all the check weigh-ins leading up to the fight and says his rival will get a shock if he takes him lightly.

"I hope he comes in and tries to take my head off, because he thinks he's just fighting a welterweight," said Brook, who is unbeaten in 36 pro fights.

"If he does that, he'll leave himself open and I'll take him out. I believe I've got the better boxing skills but I can also punch with bad intentions."

Brook's promoter Eddie Hearn said his charge was potentially "one punch away from becoming the biggest star in world boxing".

"Kell's got no fear, unlike many who have fought Golovkin, who were beaten before they even climbed into the ring," Hearn told BBC Sport.

"Whatever you do, do not rule him out. He's a British fighter willing to put it all on the line for himself and the fans. The British public should get behind him."

Only a few former welterweights have gone on to win a middleweight world title, including greats Sugar Ray Leonard, Thomas Hearns and Roberto Duran.

Virgin Islander Griffith vacated his welterweight title shortly before winning the middleweight world title from Nigeria's Dick Tiger, but he was still widely recognised as a rare simultaneous two-weight world champion.

Before dethroning undisputed middleweight champion Marvin Hagler in 1987, Leonard had been retired for three years and briefly held a light-middleweight world title in 1981.