HAMBURG, Germany (AFP) - Ukraine's Vladimir Klitschko knocked out America's Tony Thompson in the 11th round to retain his WBO and IBF world heavyweight titles.

Klitschko, who has held the IBF belt since April 2006, was fighting for the first time Saturday since taking the WBO crown off Russia's Ruslan Ibragimov in February in New York.

The 32-year-old took control of Saturday's fight from the fourth round before going on to inflict Thompson's second defeat in 33 fights.

Klitschko now has a record of 51 wins and three defeats.

Saturday's fight was his first in his adopted home city of Hamburg in eight years.

He and boxing brother Vitali moved here in 1996 following his Olympic Games victory.

"It was a tough fight and Thompson put on a great defensive effort," said Klitschko.

"It is not so easy to defend all the titles and it has been a while since I last had a black eye so today I really look like a boxer. I did not expect the victory to come that hard.

"You could see that he really wanted to win. He is a strong fighter. It was a lot of fun to fight against him."

Klitschko's next fight is expected to be in November against Russia's Alexander Povetkin, the number one IBF challenger, he will be aware that British cruiserweight king David Haye is moving up to heavyweight and watched the fight.

Haye says he is desperate to fight Klitschko after seeing plenty of weaknesses in his fight against Thompson.

"If he fights me in the same way he fought that guy he will be knocked out in three rounds," said Haye.

"He has got the perfect style for me. I don't want him to have any more fights before me as I don't want someone else to do what I will do against him."

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