UFC Rio: Heavyweight Bout Canceled After Positive Testosterone Test

‘I just found out, here’s the reason for the cancellation of the fight with Valter Walker. The test that showed elevated testosterone levels was collected in September,’ Viana stated on social media.

Usman, younger brother of former welterweight champion Kamaru Usman, was set to face Valter Walker in a pivotal heavyweight matchup. His removal from the event has raised questions about testing protocols and the timing of results, as the sample was reportedly collected nearly a month before the fight announcement.

The 36-year-old heavyweight, known as ‘The Motor’ , has quietly built a 12–4 record across his UFC career. His recent win came in June 2025 over Hamdy Abdelwahab, following back-to-back losses against Thomas Petersen and Mick Parkin. Prior to that, he scored decision victories over Jake Collier and Junior Tafa, and a memorable knockout of Zac Pauga in 2022 that earned him a Performance of the Night bonus.

This development not only removes a notable name from UFC Rio but also leaves Valter Walker without an opponent. The Brazilian rising prospect, who was hoping for his biggest test to date, will now have to wait for a rescheduled opportunity as the promotion looks for potential replacements.

While Dana White has not yet made an official statement, the UFC typically conducts its own review in partnership with regulatory commissions before issuing sanctions. Given the timing and seriousness of the result, Usman could be facing disciplinary measures that extend beyond this canceled bout.

The situation adds an unexpected twist to what was shaping up to be one of the more stacked cards of the year. UFC Rio, already drawing attention for its homegrown matchups, will now proceed without one of its marquee heavyweight attractions — a reminder that even at the sport’s highest level, compliance remains under the microscope.