David Haye will challenge Vitali Klitschko for the WBC heavyweight title next summer and has confirmed the fight is "100 per cent certain" to take place in London.
Former world cruiserweight champion Haye travelled to Germany this weekend to hold negotiations for a title shot in 2009.
Klitschko's brother Wladimir had seemed the likelier opponent but, after talks with both brothers, it was decided Haye would fight elder brother Vitali first.
The financial and logistical details have all been agreed and the fight will take place in June, probably at Wembley Stadium or Stamford Bridge.
Londoner Haye made the permanent move up to heavyweight last month with an explosive stoppage victory over highly-rated American veteran Monte Barrett, and believes the nature of that win convinced Vitali to step into the ring with him rather than his more vulnerable younger brother Wladimir, the IBF and WBO champion.
Haye told PA Sport: "It was always going to be Wladimir until my fight with Barrett.
"But Vitali was ringside for my victory over Barrett and I think he saw something in me that he doesn't want his brother getting involved in, someone like me, who isn't afraid of getting jabbed.
"I am someone who wants to go out there throwing bombs and my bombs on Wladimir's chin would equal a knockout.
"Vitali knows he has got a lot better chin (than Wladimir). He's a lot sturdier and stronger, so I think he made a family decision and put himself in the firing line."