Nathan Cleverly's light-heavyweight bout against Andrzej Fonfara will be held in Chicago on 16 October.
Polish fighter Fonfara, who is based in the American city, has a 27-3 record with 16 knockouts.
Welshman, 28, Cleverly has decided to face the 27-year-old rather than WBA champion Juergen Braehmer.
"This is a another big opportunity for me. I've had two good performances in the States but this one is on a big platform," he told BBC Radio Wales.
"It's probably the biggest fight of my life, but I'm confident. Preparations have gone well and it's just a matter now of performing.
"There's no reason for me not to perform - I'm ready, I'm hungry, I'm firing and ready to showcase against Andrzej Fonfara."
Cleverly, a former WBO light-heavyweight lost to Tony Bellew at cruiserweight in November 2014 but made his comeback at light-heavyweight with a 24-second stoppage of Czech journeyman Tomas Man last May.
Fonfara's last fight was a nine-round stoppage of former middleweight world champion Chavez Jr.
"I'm excited to return to my hometown of Chicago on this big fight night against a world-class fighter like Nathan Cleverly," said Fonfara, who will be fighting at the city's UIC Pavilion for the 14th time.
"This will be a tough fight for both of us. Cleverly is a solid fighter and it's no fluke that he was a world champion and that he defended his belt so many times."