Kell Brook faces the biggest challenge of his career against Gennady Golovkin Kell Brook faces the biggest challenge of his career against Gennady Golovkin

Gennady Golovkin will defend his world middleweight titles against Kell Brook on September 10 at London's O2 Arena, live on Sky Sports Box Office.

Brook, the IBF's current welterweight king, will jump two divisions to take on the WBA Super, WBC and IBF world middleweight champion in a bold move which echoes and even surpasses Amir Khan's decision to tackle Saul 'Canelo' Alvarez in May.

Golovkin's pedigree as a savage knockout specialist can be traced more clearly even than Alvarez's thanks to 32 stoppages in 35 unbeaten fights to date.

Brook boasts one win more than GGG and is also yet to lose, but the Sheffield man has not fought for a title above 147lbs in his career.

And the Kazakh represents a huge leap in class for Brook after three routine defences of his welterweight belt in the past 16 months, two mandatory and the other against Birmingham's Frankie Gavin.

Have a look back at some of Golovkin's best knockouts Have a look back at some of Golovkin's best knockouts

"This is the fight and the moment I have been waiting for for some time," said Brook, who will retain his status as the IBF's 147lb champ.

"We've tried and tried to lure the best to come and fight me and now we've got the best of the best - the No 1 fighter in the world is coming to the UK.

Golovkin knocked down Dominic Wade on the way to his most recent win

"When this fight got offered to me I accepted within minutes and I can't wait. Everyone knows I'm a huge welterweight and I know I will carry my speed and accuracy and even more power through the weights.

"This is the ultimate fight, one of the biggest international fights the country has seen in many years - you have seen some huge names run from GGG but I'm running to him. I'm a 'Special' fighter and I will show the world on September 10."

Brook will retain his status as the IBF's welterweight champion

Promoter Eddie Hearn said: "I cannot tell you how excited I am for this mega fight. I couldn't be happier for Kell.

"We have pushed for that big name for a long time with many reluctant to step into the ring with him and now this is the ultimate challenge, the biggest fight of 2016."

Golovkin said: "I'm very excited to be fighting in front of the great British boxing fans and promise another 'Big Drama Show' against Kell Brook."

Information on ticket on-sale dates and prices will be released early next week.