The former World golf number one Vijay Singh has denied knowingly using a substance that violated the PGA Tour's anti-doping policy.
Singh says he's angry about the situation, following a Sports Illustrated article linking the Fijian to a company called Sports with Alternatives to Steroids and its deer antler spray that purportedly helps athletic performance.
The spray contains IGF-1, an anabolic hormone that boosts muscle growth and is banned by all major sports organisations.
Singh, admits to using the spray but says he had no idea it violated PGA anti-doping rules and says he's co-operating with a PGA Tour investigation into the matter.
The article said PGA players were warned about the deer antler spray in 2011 after PGA player Mark Calcavecchia was told by the tour to stop endorsing another spray by SWATS.
Singh's 34 career PGA wins include three major titles, at the 2000 Masters and the 1998 and 2004 PGA Championships.