Unbeaten Russian Sergey Kovalev, who beat Australian Blake Caparello on Saturday, will fight Age-defying Bernard Hopkins in November.
Hopkins is trying to become an undisputed light heavyweight world champion at 50.
No exact site or date for the bout was announced, although promoters said it would be in early November on the East Coast of the US, making New York or Atlantic City likely choices.
Hopkins, the oldest major world champion in boxing history, is the International Boxing Federation and World Boxing Association champion.
He will turn 50 next January and hopes to add Kovalev's World Boxing Organization crown to his trophy haul.
"Everything I do at this point in my career affects my legacy," Hopkins said.
"I've set and broken many records, but becoming the oldest undisputed light heavyweight world champion is the goal and Kovalev stands in the way of that goal.
"He's another young, hungry fighter and just like the ones that came before him, he will leave the ring beltless."
Hopkins, 55-6 with two drawn and 32 knockouts, will try to avoid becoming the most high profile knockout victim for 31-year-old Kovalev, who is 25-0 with one drawn and 23 knockouts.
"I respect Bernard Hopkins for taking this fight," Kovalev said.
"When I came to America, it was a dream to fight the best and now I am. I have my chance."
Hopkins defeated Kazakh fighter Beibut Shumenov to win the WBA crown, becoming the oldest fighter to unify titles.
Kovalev made his third WBO title defence by stopping Australian Caparello.
Hopkins had also been interested in fighting Adonis Stevenson, a 36-year-old Haitian-born Canadian who is the World Boxing Council titleholder.Tags: Bernard Hopkins , Sergey Kovalev , Hopkins-Kovalev , Hopkins vs Kovalev