Sun Yang, one of China's biggest swimming stars, has defended his behaviour during a random drug test after a vial of his blood was smashed with a hammer.
The three-time gold medallist is fighting for his career in the Court of Arbitration for Sport (CAS) as the World Anti-Doping Authority (WADA) seeks to ban him from the sport for up to eight years.
Last September, a doping control team arrived at Sun's home in Zhejiang province for an out-of-competition blood and urine test.
Speaking through a translator, the 27-year-old told the CAS hearing he did not believe the testing agents had the proper accreditation to collect samples.
"If they don't have the correct authorisation, they are not allowed to take away the urine and blood sample," he said.
The swimmer also told the CAS that one of the agents was surreptitiously recording videos and taking photos of him.
"We started the process of having a blood test, and then I realised the anti-doping assistant was filming in the room," Sun told the CAS.
After his blood was taken, Sun refused to give the team a urine sample.
One of the agents then heard the sound of glass breaking, and went outside to find Sun's bodyguard using a hammer to break the container holding his blood vials.
"The athlete was beside the guard using his phone as a flashlight," according to the FINA Doping Report.
But Sun told the CAS that he was simply following the instructions of the testing agents after he demanded his blood sample be returned to him.
"They told us, 'it's up to you. If I can open the blood tube, you can keep it.' They needed to take the external bottle with them," he said.
Panel says Sun 'foolish' but did not break rules
Sun was investigated by FINA in January of this year, and the body concluded the swimmer committed no anti-doping rule violation.
"It is safe to describe the entire [visit] as problematic, highly unusual and, at times, confrontational," the FINA panel wrote.
However, the body criticised the "troubling and rather aggressive" conduct by Sun and his entourage.
FINA slammed Sun's decision to smash the blood vials as "foolish in the extreme."
"The athlete's entire athletic career hung in the balance on what amounted to, essentially, a gamble that the athlete's assessment of the complex situation would prevail," the panel wrote.
The World Anti-Doping Agency challenged the decision in the Court of Arbitration, but allowed Sun to continue competing at the world championships in South Korea in July.
Sun faces protests from fellow swimmers
The championships were an awkward event for Sun, with fellow swimmers publicly opposing his presence.
American swimmer Lilly King said she was not "remotely comfortable" with FINA's approach to doping allegations.
"They could start with not letting people who have smashed blood vials in tests compete in their meets. That's really sketchy," she said.
Britain's Duncan Scott refused to shake the Chinese swimmer's hand during the presentations of the men's 200-metre freestyle medallions.
And when Sun beat Mack Horton in the 400-metre final at the championships, the Australian would not share the podium with him.
The pair have been engaged in a bitter feud for years after Horton branded Sun a "drug cheat" at the 2016 Rio Olympics.
Sun served a secret three-month ban in 2014 and returned to competitive swimming before his suspension was officially confirmed by Chinese officials.
In 2014, he tested positive for the drug trimetazidine, but Sun insisted he was taking it for a heart condition.
The substance had been banned a few months before Sun failed the test.
"It was not an attempt to use a forbidden medication. It was purely a mistake," he told the CAS.