Watch | Maria Sharapova: I made a huge mistake

Maria Sharapova admitted having failed a drug test at the Australian Open. Sharapova said she tested positive for meldonium, which she has been taking for 10 years for health issues. Meldonium became a banned substance this year. The WTA has not announced a penalty. Sharapova, currently sidelined with a forearm injury, hasn't competed since losing to Serena Williams in the quarterfinals of the Australian Open in January.