IBF, WBA, WBC and IBO middleweight champion Gennady Golovkin is to fight Kell Brook in London on September 10, it has been announced.
The bout, which will see IBF welterweight champ Brook step up to middleweight, has been scheduled for seven days after the Sheffield fighter had been expected to face off against Jessie Vargas at the city's Bramall Lane stadium.
But that contest appears to have been shelved as the two undefeated stars prepare to meet at the O2 Arena.
"This is the fight and the moment I have been waiting for for some time," said Brook. "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 number one pound-for-pound 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 September 10."
Kazakhstani Golovkin, who has won 32 of his previous 35 bouts by way of knockout, added: "I'm very excited to be fighting in front of the great British boxing fans and promise another 'Big Drama Show' against Kell Brook."