Poland's Tomasz Adamek will face one of the Klitschko brothers this year - but it is not known whether it will be Vitali or Wladimir.
Fight to take place in Poland at a newly-built football stadium
Tomasz Adamek will fight one of the Klitschko brothers this year - but it has not yet been decided which one the Polish heavyweight will take on.
WBO and IBF champion Wladimir defends his belt against Dereck Chisora in April while Vitali - who currently holds the WBC title - meets mandatory challenger Odlanier Solis in March.
However the siblings have now agreed that one of them will go toe-to-toe with former two-weight champion Adamek.
The bout will take place in Poland in September at a newly-built football stadium for the 2012 European Championships.
"Adamek is very experienced, fast and a hard-punching opponent," Vitali said. "Whether it is Wladimir or me, we have to be very concentrated during the entire fight.
"It is fantastic that a Polish and a Ukrainian boxer will be together in the ring to set the first sports highlight in the run down to the Euro 2012."
Wait
Adamek will find out in April which of the siblings he will be taking on.
If both Klitschko brothers lose their upcoming fights, the deal would be off. If one loses, he will meet the other. If both win, however, the duo will decide between themselves who faces the 34-year-old next.
"I'm very happy. I would like to thank the Klitschkos for being very generous with the percentage offer," Adamek said of the deal.
"I am looking forward to this fight. It doesn't make a difference to me which Klitschko I fight. Right now they are both the biggest stars in the boxing world and I want to fight the biggest stars. I'm grateful for the opportunity."
The news is a further blow to the possibility of either Klitschko fighting David Haye in a unification showdown this year.
WBA champion Haye has a mandated defence of his own, against Ruslan Chagaev, coming up but had hoped to meet either Wladimir or Vitali before his self-imposed retirement date of October.
