Wladimir Klitschko has been confirmed for a November title defence against undefeated Pole Mariusz Wach.
The 32-year-old Wach will be the first opponent to have a height advantage against Klitschko, a factor which makes the fight interesting for the Ukranian.
Klitschko said: "The big challenge for me is Wach's height. It is the first time that I am facing an opponent who is taller than me and has a better reach.
"He is unbeaten, a big puncher and has an irrepressible will."
Wach said that he will prove doubters wrong and end Klitschko's 13-fight reign as world heavyweight champion.
He said: "My fellow countrymen Adamek and Sosnowski did not have what it takes to beat a Klitschko.
"I am not a former cruiserweight [like Adamek] but a real heavyweight. Klitschko will take a lot of hard punches before I knock him out. I will be the first Polish world heavyweight champion."
The bout will take place on Saturday, November 10 at the O2 World Arena in Hamburg, Germany.
Liam Power
