Former heavyweight world champion Wladimir Klitschko has announced his retirement from boxing at age 41.
"I never thought I'd have such a long and successful sporting career -- I thank you all from the bottom of my heart," Klitschko told his fans in an August 3 statement.
The move comes after the Kazakhstan-born Ukrainian was knocked out in the 11th round by the current world champion, Britain's 27-year-old Anthony Joshua, in April.
A proposed rematch against Joshua that was slated to be held in November will now not take place.
Klitschko says: "As an amateur and a professional boxer, I have achieved everything I dreamed of, and now I want to start my second career after sports."
Klitschko -- whose boxing brother Vitali is currently the mayor of Kyiv -- hangs up his gloves after compiling a record of 64 wins and five defeats.
Klitschko, who was nicknamed Dr. Steelhammer for his punching power, won 53 of his fights by knockout or technical knockout (TKO).
His professional career started after he won an Olympic gold medal at the 1996 Games in Atlanta. He held the majority of heavyweight boxing titles from 2006 until 2015, when he lost a decision to Britain's Tyson Fury.