Adrien Broner will move up two divisions to fight for Paulie Malignaggi's world welterweight belt on June 22.
The WBA title contest, finally confirmed after weeks of speculation, will take place on Malignaggi's home turf at Brooklyn Barclays Center.
And unbeaten Broner's decision to jump two weight classes casts severe doubt on the prospect of a lightweight unification fight with Scotland's Ricky Burns.
"Paulette better be in some shape," said the outspoken Broner, the current WBC lightweight champ nicknamed 'The Problem' who previously held the WBO super-featherweight belt.
"On June 22, I will be a three-time world champion in three weight classes at just 23-years-old."
Malignaggi, who also became a two-weight world champ when he beat Vyacheslav Senchenko a year ago, has gone five fights unbeaten since he was handed a fourth career defeat by Amir Khan in May 2010.
The New Yorker said: "This fight was the main motivation for winning my second world championship last year.
"I wanted to be in a huge main event at Barclays Center. This is a blockbuster event and I can't wait to make a successful title defence in Brooklyn where my roots are."
The scheduled undercard includes a heavyweight rematch between Johnathon Banks and Seth Mitchell, who was knocked out inside two rounds when the two met in November.