-- Pound-for-pound king and unified light heavyweight world titleholder Andre Ward said in a statement on his website that he is "leaving" boxing.
"I want to be clear -- I am leaving because my body can no longer put up with the rigors of the sport and therefore my desire to fight is no longer there," the statement said. "If I cannot give my family, my team, and the fans everything that I have, then I should no longer be fighting."
On Thursday, Ward told First Take more about the thought process behind his decision to retire.?
"People see what I do fight night," he said. "They see under the lights, but they don't see the toil, they don't see the grind, they don't see just the pain, the physical pain that you go through, not just in the fights, but to prepare and to get ready for those battles.
"I felt the physicality of the sport, not just in the ring stuff, but the training and the preparation, start to take its toll on me for the last two or three years, and I bit down and continued to push through, and at this point, it's time, and I know it's time."
Last month, Ward told ringside media that his television contract with HBO is up.
He added that, contrary to industry chatter, he remains under contract with promoter Roc Nation Sports, even though rumors have swirled that he was gearing up for a jump to Top Rank.
Ward (32-0, 16 KOs), of Oakland, California, has been with HBO since he knocked out Chad Dawson in 2012, though Ward has had two long layoffs since because of promotional issues.
Ward, 33,?has fought six of his past seven fights for HBO, including both of his pay-per-view fights with Sergey Kovalev -- a controversial unanimous decision win in November to take Kovalev's three 175-pound world title belts, followed by an eighth-round knockout victory in the rematch on June 17.
"Andre Ward ends his boxing career as he only knew how to live it -- as a champion at the top," Peter Nelson, executive vice president of HBO Sports, said in a statement. "To watch Ward was to marvel at constant mastery of craft in the ring, to say nothing of his being the consummate role model outside it. The Hall of Fame will be lucky to have him.
"We wish Andre and his family much success and happiness as he explores new opportunities, including with our own HBO family as one of the expert analysts on our broadcast team.
"It was a privilege for HBO to serve as the television platform for many of his landmark achievements in the sport he loves."
ESPN's Dan Rafael contributed to this report.