New theory could be key to Willie Rioli drug test defence

Could severe dehydration and a negative blood test hold the key to AFL forward Willie Rioli's urine-tampering defence?

Rioli is facing a ban of up to four years after the star West Coast goalsneak allegedly tampered with his urine sample during a routine ASADA drug test on August 20.

It's been reported a frustrated Rioli poured a sports drink into the sample container after going hours without being able to pass urine.

The West Australian reported Rioli has told people around him he acted naively and in frustration rather than purposely trying to subvert the testing process.

Willie Rioli is accused of tampering with his urine sample. Pic: Getty

The results of a subsequent blood test could prove crucial in Rioli's defence.

But even if that blood test shows up negative to any performance-enhancing or illicit substances, Rioli could still face the maximum penalty of four years.

Tampering with a urine sample is viewed as more serious than returning a positive drug result and ASADA may not take into account any extenuating circumstances such as dehydration or the results of follow-up testing.

West Coast star’s case could be a lengthy one

Rioli will be represented by David Grace when he appears before the anti-doping tribunal.

It's unknown how long the matter will take to resolve but it could take six months or more.

Rioli will be provisionally suspended throughout that period.

The controversy erupted just days before West Coast's semi-final against Geelong at the MCG last Friday night.

Eagles players looked flat early in that game, with Geelong going on to win by 20 points to end the Eagles' flag defence.