Wladimir Klitschko earned the 17th defence of his world heavyweight boxing crowns with a fifth-round knockout of Kubrat Pulev to secure the 53rd KO of his career.
The 38-year-old inched closer to Joe Louis' record of 25 heavyweight defences when he put the Bulgarian down for the fourth time after two minutes, 11 seconds of the round.
The Ukrainian retains his IBF, IBO, WBA and WBO belts to remain the undisputed heavyweight champion of the world after the 63rd victory of his career.
Pulev was twice on the canvas in the first round after explosive starts by the world champion and the International Boxing Federation's mandatory challenger.
The Bulgarian was quickly on his feet, grinning and balancing on one leg in a bid to prove he was unaffected, but Klitschko was soon on top.
Klitschko put Pulev on the canvas with a fierce left hook in the third round, as a cut opened under the challenger's left eye, but he survived referee Tony Weeks' count.
It is more than a decade since Klitschko's last defeat - to Lamon Brewster in April 2004 - and the champion was clearly on top by the fourth round.
Klitschko caught Pulev flush in the face with a left hook early in the fifth round and another ended the fight as the Bulgarian went down for the fourth and final time.
The defeat was the first of the 33-year-old's career after 11 knockouts in 20 victories.