Nigerian hurdling sensation Tobi Amusan has been charged by the World Athletics Integrity Unit (AIU) for allegedly missing three drug tests within a 12-month period, a potential anti-doping violation.

Amusan revealed the allegations herself on social media early Wednesday after winning the 100m hurdles event at the Gyulai Istvan Memorial meet in Hungary on Tuesday. The 25-year-old crossed the line in 12.35 seconds, edging American rivals Nia Ali and Alaysha Johnson.

In an Instagram post, Amusan denied any wrongdoing and vowed to challenge the AIU charges before an independent three-member tribunal ahead of August’s World Championships in Budapest.

“I am a CLEAN ATHLETE and have FAITH this will be resolved in my favor,” she wrote. Amusan claims she was tested by AIU days after one of the “missed tests.”

Under anti-doping rules, athletes must make themselves available for random out-of-competition testing at their listed whereabouts. Missing three tests in 12 months can trigger an investigation.

Amusan will have to clear her name quickly to defend her 100m hurdles world title. The AIU charges come despite her stellar form, having also won the Diamond League event in Silesia last Sunday.