Allyson Felix, an 11-time world champion and six-time Olympic gold medallist, finished third over 400m at a meeting in Marseille on Saturday before insisting that she hasn't given up on matching Usain Bolt's record of eight Olympic titles in Tokyo in 2020.
American star Felix was beaten on Saturday by Italy's Libiana Grenot, the European champion, with Drayton Shakes of Great Britain taking second place.
"It wasn't a great evening for me. I hope to do better but this year is very different," said 32-year-old Felix, the most decorated female athlete with a total of nine Olympic medals and 16 at the worlds.
"I'm a long way off my best form but I am going home now to work." Felix, the 200m champion at the 2012 Olympics in London and silver medallist over 400m in Rio in 2016, has her eyes set on another title when the 2020 Games roll around in Japan in two years' time.
"In team but especially in the individual events, I hope to be a champion in Tokyo.
"This year is important as preparation for 2019 (when the world championships are held in Doha).
"Each season is a new challenge and I think that I haven't yet reached my maximum.