MOSCOW, June 11 (RIA Novosti) - IBF and WBO Heavyweight Champion Wladimir Klitschko of Ukraine has predicted a tough June 20 fight against WBA champion in recess Ruslan Chagaev, the FightNews.com reported on Thursday.

The much-anticipated June 20 fight in Germany between Wladimir Klitschko and undisputed cruiserweight champion David Haye of Britain was canceled last week after the Londoner pulled out with a back injury he picked up in training.

Klitschko (52-3, 46 KOs), although disappointed by Haye's injury, said he would nevertheless stick with the date for the fight and scheduled a bout with 30-year-old Chagaev (25-0, 17KOs).

"I decided to not cancel the fight on June 20th because I don't wish to upset the fans. There will be an overflow crowd and it will be an excellent fight," the website quoted Klitschko as saying.

"For me it's a difficult fight. I have just two weeks for preparation," he said. "Ruslan Chagaev is a lefthander [Klitschko had been preparing for right-hander Haye] but I have experience and victories over strong southpaws like Sultan Ibragimov and Tony Thompson."

Chagaev was scheduled to fight Russia's WBA Heavyweight Champion Nikolai Valuev (50-1, 34 KOs) on May 30 in Helsinki, but the bout was called off after the champion in recess was diagnosed with a mild form of Hepatitis B and was unable to meet the Finnish boxing federation's medical requirements.