'Sky's the limit' for 800m world champion Mu
The 21-year-old sliced almost six seconds off her personal best to advance from the 1,500m heats at the US athletics championships in Eugene, Oregon.
While the event remains, for the moment, largely a training exercise, Mu said that might not always be the case and she could potentially challenge on the international stage from 400m through the 1,500m.
"I feel like every race -- four, eight or 15, I haven't gotten my fullest potential out," Mu said. "And I think being with a coach like Bobby, he knows how to get that level.
"I feel like I'm still kind of an amateur just in terms of reaching my potential. So I think the sky's the limit."
Mu held off a late challenge from Britain's Keely Hodgkinson to add the 800m world title to her Tokyo Olympic gold at the World Championships in Eugene last year.
She became the youngest woman in history to own Olympic and world titles in an individual track and field event, and soon after moved from Texas to Los Angeles to train with Kersee.
With a bye into the 800m at the August World Championships in Budapest, Mu opted to race the 1,500m at the US trials, but even should she qualify with a top-three finish a double remains unlikely.
"I don't know if I should like make you guys go crazy and say yes," she laughed when asked about a double, "or if I should just tell you the truth: Probably not."
She wasn't even 100% sure she'd race the final on Saturday, saying she'd wait to see how she recovered.
Flexibility, and racing sparingly, is something Mu said she's enjoying after a pair of pressure-filled seasons that featured the pandemic-delayed Tokyo Games and last year's postponed worlds on home soil.
She got her first 800m victory under her belt in her 2023 season debut at the New York Grand Prix in June.
"I haven't really put myself out there as much," she said. "Just the overall pressure that you feel when it comes to competing is a lot.
"We just wanted to step back and just be my 21-year-old self -- just enjoy life for a little bit."