Seven-time Olympic champion Allyson Felix has announced 2022 will be her final year of competition.
The 36-year-old, who indicated last year she would not seek to compete in a sixth Olympic Games in Paris in 2024, shared the news on Instagram.
"As a little girl they called me chicken legs, never in my wildest dreams would I have imagined I'd have a career like this," the 13-time world champion wrote.
"I have so much gratitude for this sport that has changed my life. I have given everything I have to running and for the first time I'm not sure if I have anything left to give.
"I want to say goodbye and thank you to the sport and people who have helped shape me the only way I know how - with one last run.
"This season isn't about the time on the clock, it's simply about joy. If you see me on the track this year I hope to share a moment, a memory and my appreciation with you."
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Felix had previously indicated a desire to continue racing this year, with the fact the world outdoor championships will be in Eugene, Oregon, part of her decision.
In Tokyo last summer Felix was part of the United States' gold-medal winning 4x400m team and also took 400m bronze to pull level with Carl Lewis' American record for 11 Olympic medals in athletics.
She was competing in Japan less than three years after a life-threatening emergency C-section to deliver her premature daughter.
Felix added: "This season I'm running for women. I'm running for a better future for my daughter. I'm running for you. More to come on that, so stay tuned, but I'll be sharing a series of announcements that I'm hoping will make the world better for women.
"Here's to my final season"