The Athletics Integrity Unit (AIU) has appealed the decision that exonerated Nigerian hurdler, Tobi Amusan from a violation for missing drug tests.
The anti-doping regulators claimed it filed an appeal at the Court of Arbitration for Sport late last week.
It provisionally suspended Amusan for missing three tests in a year.
An appeal panel later overturned the suspension, which allowed the Nigerian to compete earlier this summer at the world championships, where she finished sixth.
If found guilty, the 26-year-old might be suspended for a year or more.
Amusan won the Diamond League title for the third consecutive year last weekend.