Former WBO heavyweight champion Wladimir Klitschko continued his comeback bid with a one-sided win over Cuba's Eliseo Castillo in Dortmund.
Klitschko's win delighted the 10,000-strong German crowd
Klitschko has seen his career falter of late with defeats to Corrie Sanders and Lamon Brewster in the last two years.
But he was impressive against Castillo and sealed a fourth-round win when the Cuban failed to beat the count after being floored by a big right hand.
"I hope to fight for the world title again," Klitschko said afterwards.
"Things are looking pretty good in the IBF, where Chris Byrd holds the belt. I am confident of getting a chance in the next two fights."
Klitschko started the bout well and kept Castillo at bay with his sharp left jab.
The previously unbeaten Cuban was never really in the contest and was at the wrong end of two massive rights in the second before he was knocked down with 20 seconds of the fourth remaining.