Doha: Ukraine’s former heavyweight world champion Wladimir Klitschko retired from boxing thus ruling out a rematch with Britain's Anthony Joshua.
The 41-year-old was knocked out in the 11th round by current champion Joshua at Wembley Stadium in April.
Joshua, 27, had hoped Klitschko would sign his rematch clause for a proposed fight in Las Vegas on November 11.
Klitschko announced his retirement on his www.klitschko.com, and posted a video on his official Twitter account.
"I’ve achieved everything I dreamed of, and now I want to start my second career after sports,” said Klitschko.
The 41-year-old Ukrainian was knocked out by Joshua in the 11th round at Wembley Stadium in April.
The two-time former champion, who held the unified title from 2006-2015 before losing to Joshua’s fellow Briton Tyson Fury, ends his career with a record of 64 wins and five defeats.
“I would’ve never imagined that I would’ve such a long and incredibly successful career,” he added.