Undisputed world heavyweight champion Wladimir Klitschko claimed the 50th knock-out and 57th victory of his career when he ended hapless Frenchman Jean-Marc Mormeck’s hopes in the fourth round late Saturday.

Klitschko, 35, defended his IBF, IBO, WBO and WBA titles against Mormeck, who stepped up from cruiserweight just over two years ago, in Dusseldorf and made good on his promise to knock the Frenchman out.

“I’m delighted to get the 50th knock-out of my boxing career, I promised and I delivered,” said Klitschko, who had a 17-centimetre height advantage over his rival from France.

His elder brother Vitali, who was in his corner, confirmed he will defend his WBC title against Britain’s ex-WBA champion David Haye this summer, but did not give a date or location.

Mormeck, who turns 40 in June, was lucky to finish the second round after Klitschko put him on the canvas with 80 seconds left in the round with a firm right to the chin and then pinned him in a corner with a rapid combination of punches.

The challenger was offering only token resistance and made a mockery of his pre-fight promises to smash Klitschko’s “glass jaw” which was as ineffective as the handful of punches he threw in the opening rounds.

The pair both ended on the canvas in the third after a slip, but it was all over in the fourth when a swift combination from the champion saw the Frenchman drop his guard and a final head shot left Mormeck on the canvas.