Anthony Crolla will make the second defence of his WBA lightweight title against Venezuela's Jorge Linares in Manchester on September 24.
Crolla stopped another Venezuelan, Ismael Barroso, in his last fight in May having ripped the crown from Darleys Perez by knockout last November.
Linares was declared the WBC's lightweight champion in recess last week, allowing Montenegrin Dejan Zlaticanin to win the vacant title in the US at the weekend.
Nevertheless, the bout between Crolla and Linares is being promoted as a unification contest with the WBC's 'Diamond' belt - purportedly held by Linares - on the line.
Despite the questionable billing it is another big test for Crolla against Linares, who climbed off the canvas to stop Kevin Mitchell in London in May.
Crolla said: " Jorge is a fantastic fighter and it's another mountain to climb, but these are the tests that I thrive on and I've beaten two great fighters in Perez and Barroso and I'm confident that I can beat Jorge too.
"I've been a fan of Jorge Linares for years now and he's technically brilliant at times but like any other fighter, he has vulnerabilities. It's up to me to expose those vulnerabilities and I truly believe that I can and I will. Linares is a great champion but these are the fights you want to be in boxing for."