The veteran southpaw, 36, was on top for most of the bout against the unfancied Konrad and pleased the crowd in recording the 35th stoppage of his career in Dresden, Germany.
In the co-feature, cruiserweight Mateusz Masternak put his career back on track following his highly controversial points reverse against Jonny Muller in South Africa by halting Brazilian Carlos Nascimento in the second.
Over in Hollywood in the United States, ex-WBO heavyweight champion Shannon Briggs took just over five minutes to put the 52nd knockout of his career in the record books against Michael Marrone.
The 43 year-old was far too powerful for the former cruiserweight world title challenger and had Marrone, 29, in trouble from the very first round.
In the second, Briggs stepped up his work and delivered a beautiful head, body combination to end the fight there and then with Marrone sprawled on the canvas.
Briggs is still pining for a shot at current top division king Wladimir Klitschko and was filmed squaring up the Ukrainian once again earlier in the week.