The long-awaited season debut for Athing Mu will have to wait. 

Mu's coach Bobby Kersee told Runner's World on Wednesday that Mu will scratch from the women's 800m at the Prefontaine Classic on Saturday in Eugene, Oregon out of caution. 

The 21-year-old has been nursing a left hamstring injury, he said, and "it was not worth the risk to race on it." 

Mu's anticipated start to the 2024 season was building last week as she was entered in the 400m at the LA Grand Prix. She dropped just a few days before the event. Mu told Runner's World recently that her last year of training and competition has been "pretty rough." 

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This year's women's 800m field at Prefontaine was a chart-topper, with the likes of Keely Hodgkinson, Mary Moraa, Tsige Duguma, Jemma Reekie, Raevyn Rogers and Nia Akins. The field could in large part be a preview of an Olympic final in Paris. 

The timing is of concern, especially with the onset of the U.S. Olympic Trials set to begin on June 21 in Eugene, Oregon. 

Mu dazzled with an incredible performance at 800 meters during the Diamond League final at Prefontaine last September, winning in a career best and American record of 1:54.97, doing so across a star-studded field that included Olympic silver medalist Keely Hodginson and World champion Mary Moraa. 

They were the very two individuals Mu lost to at the World Championships. 

Mu remains, however, as the woman to beat. She's the defending Olympic champion and followed with a 2022 World title before being defeated by Moraa in 2023. 

Mu won't have much time to figure things out on the track. The first round of the women's 800m is on the first day of action at the U.S. Trials on June 21. 

"She's a veteran, if she's healthy, she can make the team," Kersee told Runner's World. "And so, if I injure her before, I'm gonna be called a fool; If I don't race her before, I'm gonna get (criticism)." 

Historically, though, Mu has always stepped up her game. Before Prefontaine last year, her three best performances came at the Trials, the Olympic Games and Prefontaine in 2021. 

She claimed an Olympic title in 2021 in Tokyo, clocking a time of 1:55.21, a time that only paled in comparison to her output at Prefontaine that same year 1 in 1:55.04.

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