Two new cases of doping with clostebol, the substance also discovered in Jannik Sinner in 2024
Article by Luminița Paul – Published on Wednesday, 13 May 2026, 18:09 / Updated on Wednesday, 13 May 2026 18:11
The Tennis Integrity Agency (ITIA) has temporarily suspended two players, Karlis Ozolins (Latvia) and Daniil Kakhniuk (USA), after they tested positive for clostebol, the substance also found in the doping case of ATP leader Jannik Sinner.
Karlis Ozolins (23 years old, 546th place ATP) and Daniil Kakhniuk (23 years old, world number 1,123) were provisionally suspended, the Tennis Integrity Agency announced in a statement, after both tested positive for the banned substance clostebol.
Both players tested positive at an ITF tournament in San Jose (Costa Rica) on February 17, 2026, with samples containing clostebol metabolites.
It is classified as an anabolic agent on the World Anti-Doping Agency's list of prohibited substances, being banned under the Tennis Anti-Doping Program. Given the nature of the substance, ITIA stated, a provisional suspension is mandatorywith both sanctions taking effect from April 14, 2026, the ITIA announcement stated.
Both Ozolins and Kakhniuk have the right to appeal the suspensions, but they did not exercise it.
As in all cases under the Tennis Anti-Doping Program, both players benefit from the ITIA's support, including pro bono legal assistance, independent personal welfare support and financial assistance to investigate the cause of the positive results.
During the suspension, players are not permitted to participate as players or coaches in, or attend events organized or sanctioned by the ITF, WTA, ATP, Grand Slam tournaments or any national associationit is specified in the press release of the Tennis Integrity Agency.
Clostebol, discovered in Jannik Sinner's positive case
Ozolins played six matches at the ATP level, winning two and losing four and having a total of $30,517 in prize money. He has not played since March, when he won the ITF M15 tournament in Maanshan (China). He was a semifinalist in San Jose, where he tested positive, defeated by the American Gavin Young (993 ATP).
Kakhniuk it comes after reaching a career-best ranking of world No. 1111 on April 20 this year. He last played at the ITF M25 tournament in Las Vegas, where he lost in the second round, coming from the qualifiers. He still has a quarter-final in Bakersfield (U25) and a semi-final in Sherboorke (U15) in 2026, while in San Jose he was beaten in the second round after qualifying.
Jannik Sinner, one of the tennis players caught doping in 2024/Photo: Getty Images
Clostebol came into the public eye after the doping case of world number 1 Jannik Sinner in 2024. He tested positive in March of that season during the Indian Wells tournament. Less than a year after winning the 2025 Australian Open, he accepted a three-month suspension. He thus missed the Masters 1000 tournaments in Indian Wells, Miami, Monte Carlo and Madrid, returning to the competitions in Rome.
