Great Britain's Jessica Ennis-Hill finished fourth in the women's 100m hurdles at the Anniversary Games in London.
It was the first time that the 27-year-old, who claimed gold at the Olympics in the heptathlon last year, had competed since overcoming an Achilles injury.
She crossed the line in 13.08 seconds behind winner Sally Pearson, Briton Tiffany Porter and Kellie Wells.
"This was very nerve-wracking. It was my first race back and I couldn't prepare as best as I wanted. I was disappointed with my time. I'm lacking speed work at the moment having just started training this week," she told BBC Sport.
Ennis-Hill is expected to be part of the Team GB squad that will compete at the World Championships in Moscow next month.