Gennady Golovkin was searching for someone to fight him for the middleweight title. Kell Brook was more than eager to step up for the challenge.

Brook will move up two weight classes to face the fearsome Golovkin on Sept. 10 in a clash of unbeaten champions. The British fighter will have the hometown advantage at London's 02 Arena, but faces a formidable task against a fighter who is not only bigger but has stopped his last 22 opponents.

Brook got the fight after negotiations with middleweight Chris Eubank Jr. broke down this week, promoter Tom Loeffler said. The two sides quickly came to a deal, on the same terms that Eubank rejected.

Golovkin had hoped to get Mexico's Canelo Alvarez in a middleweight showdown, but turned elsewhere after Alvarez gave up his piece of the 160-pound title rather than meet him in September. Golovkin wanted to fight in London, so getting a British opponent was a priority.

Brook is more than just an opponent, having won all 36 of his fights while capturing a piece of the 147-pound title. But his first test as a middleweight will be a big one against the increasingly popular Triple G.

Take away the weight difference, and the matchup is an intriguing one. The two fighters have 71 fights between them, and 71 wins.

Just as importantly, both can bang, with Golovkin scoring 32 knockouts in his 35 fights, and Brooks 25 in 36 fights.

They will meet for the 160-pound titles held by Golovkin, who will be defending his belts in yet another major city as he works to expand his following. Golovkin sold out Madison Square Garden in October for a stoppage of David Lemieux, and did the same in April at the Forum in Los Angeles when he knocked out Dominic Wade.

Brook has fought almost exclusively in England, though he traveled to Los Angeles in 2014 to win the 147-pound title from Shawn Porter. He has defended it three times.

The fight will be televised on Sky Box Office pay-per-view in Britain, and on HBO in the U.S.