British heavyweight Dillian Whyte reportedly tested positive for a banned substance before his fight with Oscar Rivas on July 20.

The Brixton fighter won the bout courtesy of a unanimous decision, despite being knocked down by Rivas in the ninth-round.

However, Whyte's biggest win to date could be shrouded in controversy after Boxing Scene broke the news late last night of a reported failed drugs test.

A sample from Whyte is said to have tested positive for one or more banned substances.

The test was conducted by UK Anti-Doping (UKAD), but the information was said to have not been passed on to Rivas' camp.

Had the the WBC been made aware of the findings, they likely would not have sanctioned the winner of the fight becoming the mandatory for the champion, Deontay Wilder.

Whyte's Camp and the British Boxing Board of Control (BBBoC) were reportedly made aware of the news on July 17, but the fight still went ahead.

Due to rules in the United Kingdom, Whyte has the right to appeal the findings.

Until the full process is complete, the BBBoC cannot implement any sanctions and cases can take up to a year to complete.

Whyte famously served a two-year ban from UKAD back in 2012 after testing positive for a banned substance.

The 31-year-old is in the World Boxing Council Clean Boxing Program, but those tests are administered by the Voluntary Anti-Doping Association (VADA).

This sadly could be the start of something big.