Rhasidat Adeleke has pulled out of Friday night's Diamond League 400m in Monaco.
As yet, no reason has been given for the 22-year-old's withdrawal from a race she won last year.
Adeleke was a distant fourth (clocking 51.33) in the Diamond League in Eugene, Oregon last weekend, running well below her best.
A year ago she ran 49.17 in Monaco to beat the Netherlands' Lieke Klaver and USA's Kendall Ellis.
This week's setback is an unwelcome disruptor for Adeleke, who is building towards September's World Athletics Championships in Tokyo.
