Gennady Golovkin's next fight will be with welterweight champ Kell Brook

Gennady Golovkin will face welterweight titleholder Kell Brook for the unified middleweight titles on Sept. 10 in London

Gennady Golovkin's next opponent stunned many as the unified middleweight champion selected a bout with IBF welterweight titleholder Kell Brook at the O2 Arena in London on Sept. 10.

Golovkin was in negotiations to fight British middleweight contender Chris Eubank Jr., but after Eubank Jr. reportedly turned down the fight, the middleweight star turned his attention to Brook, who has the same promoter as Eubank Jr. in Eddie Hearn. The fight announcement came out of nowhere and shocked the boxing world, but it's a welcome surprise to see two talented fighters come to an agreement to meet in the ring.

Brook will look to avoid the same fate that fellow British welterweight star Amir Khan faced when he jumped up in weight to face Canelo Alvarez in May, ending with Khan being floored by one of the knockouts of the year. Brook is ranked as one of the top two welterweights in the world, depending on which outlet you look at, so his boxing skill is not in doubt.

No matter the outcome of September's bout with Golovkin, Brook will retain his IBF title at 147 pounds and, despite having never fought above 147 pounds, Brook thinks that as a naturally bigger welterweight, he will be able to make the 13-pound leap to 160 pounds.

"This is the fight and the moment I have been waiting for for some time," said Brook to Sky Sports. "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. 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 Sept. 10."

Golovkin and Brook have both hoped for big fights only to see the best in their respective divisions pass on bouts, so the matchup makes sense. Golovkin gets his wish of fighting on a big stage, making his London debut at the massive O2 Arena, and also was able to convince Brook to take the fight at the full middleweight limit of 160 pounds, something that Canelo's camp balked at.

Boxing fans should be thrilled by the news of this fight. While it's not Canelo-GGG, it is a massive fight with two of the best in the sport facing each other in their primes, one of the ultimate rarities in boxing.