Two-weight world champion Andre Ward - widely considered the best pound-for-pound fighter in the world - has retired from boxing at the age of 33.
The former super middleweight and current light-heavyweight king, who is unbeaten in the ring since the age of 13, won all of his 32 contests as a professional as well as a gold medal at the 2004 Olympic games.
The 33-year-old made the announcement on Thursday, claiming his desire to fight had disappeared because his "body can no longer put up with the rigours of the sport."
Ward, who last fought in June against Sergey Kovalev, posted a video chronicling his journey from boyhood boxer to world champion with the caption: 'Mission Accomplished'.
Ward, the last American man to win Olympic gold, first won a world title in 2009, when he beat Mikkel Kessler to win the WBA super middleweight crown.
He went on to win the innovative 'Super Six' tournament, beating Britain's Carl Froch in the final in 2011 and unifying the division in the process. He then became a two-weight king in 2016, beating Alexander Brand to pick up the WBO light-heavyweight belt, before two memorable unification bouts with Kovalev.
Ward won a highly contentious decision victory in November before cementing his place at the top of the boxing world with a stoppage of the Russian in a rematch seven months on.
He had been linked with a move up to heavyweight, with talks taking place over a possible fight with Britain's Tony Bellew. But the 33-year-old has instead called time on his glittering career.
"To the sport of boxing - I love you. You've been by my side since I was 10 years old," Ward stated.
"You've taught me so much. You've humbled me. You've promoted me. I've sacrificed a lot for you, but you've given me more than I ever thought possible.
"You gave me a platform, made me a champion and helped me provide for my family. I am forever grateful to you. You and I will always be synonymous, connected at the hip.
"Thank you for all the wonderful people I've come in contact with because of you. I've made friends for like. As I walk away from the sport of boxing today, I leave at the top of your glorious mountain, which was always my vision and my dream. I did it. We did it.
"From the bottom of my heart, thank you to everyone who has played a part in my journey. You know who you are. I could not have done this without you. 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.
"If I cannot give my family, my team and the fans everything that I have, then I should no longer be fighting. Above all, I give God the Glory, for allowing me to do what I've done, for as long as I have."