ATHLETIC BILBAO star Yeray Alvarez tested positive for a banned substance after playing Manchester United last season.The defender failed a doping test after the Europa League semi-final first leg in May.GettyYeray Alvarez failed a drugs test after playing against Man Utd[/caption]He has been suspended by the Spanish FA pending an investigation.Alvarez, 30, protests his innocence claiming the banned substance came from a hair loss preventative medication he took.He developed alopecia after twice battling testicular cancer.The Bilbao star released a statement confirming an investigation is underway.He said: “A few weeks ago, I was informed that I had tested positive in a Uefa doping test after the first leg of the Europa League semi-final against Manchester United.“Receiving this news was a huge blow, and I honestly couldn’t believe it, given that I’ve never used any banned substances in my life.“Since overcoming my illness, I have been undergoing treatment for alopecia for years, and after reviewing the case, we have determined that the positive result was due to my unintentional ingestion of a hair loss preventative medication containing a prohibited substance.“The disciplinary proceedings are currently under investigation and are subject to confidentiality, so I am provisionally suspended and not authorised to make any further public statements.“I want to tell you all that I deeply regret this situation, but with the Club’s support, I am working on my defence, confident that I can return to the field as soon as possible. Once the process is complete, I will provide all the necessary explanations.“I want to thank Athletic Club for their support and backing from the very beginning and express my confidence in the justice system and sports institutions.”