Birmingham middleweight Matthew Macklin will meet world champion Sergio Martinez on 17 March in New York.
Former European champion Macklin, 29, will fight for the first time since losing a controversial split decision to WBA champion Felix Sturm in June.
Argentine Martinez, the WBC's so-called 'diamond' champion, was last seen beating Macklin's fellow Brit Darren Barker last October.
Macklin said: "I think he knows he is in a real fight."
The bout will take place at the iconic Madison Square Garden on St Patrick's Day - a significant occasion for the city and for Macklin, who was born to Irish parents.
"The press conference was absolutely packed out, I couldn't believe it," he said. "It was huge. It brings it home how big this is.
"Coming face-to-face with Martinez, he comes across as a nice, humble, friendly kind of guy and you can't read too much into it.
"Actions speak louder than words anyway so you can't gauge whether he's nervous or not, or whether he's looking past me, just from that."
Although Martinez is widely regarded as the best middleweight in the world, there will be no sanctioned belt on the line.
He was stripped by the WBC for refusing to defend the belt against number one challenger Sebastian Zbik but remains the governing body's de facto champion in the eyes of mosty observers.
The 36-year-old has lost only once in the last 12 years and his last fight resulted in an 11th-round stoppage of Londoner Barker.