Klitschko, 37, was in control and easily ahead on all three scorecards before Peter decided against coming out for the ninth round.
Afterwards the champion, who last fought in 2004 when he beat Danny Williams in Las Vegas, admitted he had endured a difficult build-up to the clash.
He told Setanta Sports: "It was not an easy fight, it was not easy preparation. I have had so many injuries but now I am fit and healthy. I have my skills, I can't lose my skills. If I am fit and healthy I can show a good performance.
"If you want very much, have big will and support from your team, family and my brother, I can do anything."
The victory means that Klitschko and his brother, Wladimir, are now both world heavyweight champions at the same time.



