On the weekend, the International Tennis Integrity Agency revealed that the two-time Grand Slam winner failed a drug test she took at the 2022 US Open. Halep tested positive for Roxadustat, a drug that stimulates the production of red blood cells and is used in the treatment of patients with kidney issues.
In the wake of the announcement, an astonished Halep described it as the "biggest shock" of her life. Now Cahill, who coached Halep to her first Grand Slam title and the world number one spot in 2018, has come out to defend his former student.
"Firstly, and most importantly, there is NO chance Simona knowingly or purposely took any substance on the banned list. None. Zero," he wrote on Instagram in a lengthy post.
"She is an athlete that stressed about anything prescribed to her by a medical professional (which was rarely), or about any supplement that she used or considered. Simona wore out the words 'please double check this, triple check this to make sure it's legal, safe and permitted. If you are not sure, I'm not taking it'.
"We both believe in the ITIA testing program and would often discuss the number of times she was tested, both at tournaments and randomly. She did it without complaint, with the reassurance of knowing other athletes were being tested just as frequently. Competing against clean athletes was important to her. It's important to everyone and while the system is not perfect, it works.
"Simona's integrity is faultless, she respects her peers, she loves the game and she always has her feet firmly planted on the ground as a humble, approachable champion.
"Due process will now follow to reveal answers to many questions. As Simona said, the hardest match of her life starts now. I believe in her. I always have and can honestly say never more than right now on this particular issue.
"I stand with Simo."