Five-time Grand Slam tennis champion Iga Swiatek accepted a one-month suspension after testing positive for the banned substance trimetazidine (TMZ), the International Tennis Integrity Agency (ITIA) announced Thursday.

Swiatek, however, maintains the result was an unintentional contamination from melatonin she took to manage jet lag.

The suspension stems from an out-of-competition test in August, with Swiatek admitting to the anti-doping violation earlier this week. The ITIA ruled her fault as “at the lowest end of the range for no significant fault or negligence.”

Swiatek has already served the majority of her suspension, which began with a provisional ban on September 12. This caused her to miss three tournaments in Asia, including the Korea Open, Wuhan Open, and China Open—originally cited as absences for “personal reasons.” She also forfeited $158,944 in prize money earned from her semifinal appearance at the Cincinnati Open in August.

Swiatek described the ordeal as the “worst experience of my life,” sharing her perspective in an emotional Instagram post.

“In the last 2½ months, I was subject to strict ITIA proceedings, which confirmed my innocence,” she said. “The only positive doping test in my career, showing unbelievably low levels of a banned substance I’ve never heard about before, put everything I’ve worked so hard for my entire life into question.”

The provisional suspension dropped Swiatek from the No. 1 world ranking, a position she had held for much of the past two seasons, to No. 2 behind Aryna Sabalenka.

Despite the setback, she added: “Now everything has been carefully explained, and with a clean slate, I can go back to what I love most.”

Swiatek will be eligible to return to competition on Monday.