Josh Warrington will make the third defence of his IBF featherweight title against little-known Frenchman Sofiane Takoucht on October 12 at the First Direct Arena in Leeds.
The Leeds fighter retained his crown at the same venue with a split decision points victory over fellow Yorkshireman Kid Galahad in June.
Warrington had been chasing a unification bout but will instead take on a 33-year-old opponent who has won 35 of his 39 professional contests and is placed fourth in the IBF rankings.
Warrington said: "From what I've seen, Takoucht is tough and got his IBF ranking through hard work.
"This is a massive opportunity for him. I have to stay focused and not take my eye off the ball because I am after the biggest fights in the division."
Warrington, who has won all 29 of his contests in the paid ranks, wrenched his version of the world title from Lee Selby in May 2018 before outpointing Carl Frampton last December.
The 28-year-old had hoped seeing off mandatory challenger Galahad would lead to a fight against any of the other 126lbs titlists but that has failed to materialise.
Warrington's promoter Frank Warren said: "We wanted to make the Oscar Valdez unification fight for Josh, but he is giving up the WBO title and moving up in weight.
"I know how much Josh wants the WBA champion, Leo Santa Cruz, but he doesn't seem keen right now.
"If you look at the IBF ratings number one and two are vacant, and Takoucht was pretty much the next available contender."
Takoucht is on an eight-fight winning streak and, although he has never before competed in England, the southpaw believes he can spring a massive upset.
He said: "When the call came to travel to Leeds and challenge Josh I said, 'yes' straight away. It's a chance to beat the best featherweight in the world.
"He beat Lee Selby when nobody thought he could win and then a great fighter, Carl Frampton. It was close against Kid Galahad but he found a way to win.
"I am sure he will look at me and think I am easier than his last three opponents, but I won't let this opportunity go. Get ready for a shock."