LOS ANGELES, Calif. - Tennis star Maria Sharapova says she failed a drug test at the Australian Open.

The five-time major champion took full responsibility for her mistake when she made the announcement at a news conference Monday in Los Angeles. The former world No. 1 doesn't know what sanctions she will face from the International Tennis Federation.

The 28-year-old Sharapova said she tested positive for meldonium, which she said she has been taking for 10 years for numerous health issues. Meldonium became a banned substance this year under the WADA code, and Sharapova claims she didn't notice its addition to the banned list.

"I know that with this, I face consequences," Sharapova said. "I don't want to end my career this way, and I really hope I will be given another chance to play this game."

Sharapova's penalties could range from a multiyear ban to a minimal sanction with no suspension if officials believe she made an honest mistake.

"I have to take full responsibility for it," Sharapova said. "It's my body, and I'm responsible for what I put into it."

Sharapova said she tested positive in an in-competition test at the Australian Open, where she lost to Serena Williams in the quarterfinals on Jan. 26. Sharapova hasn't played since while recovering from a forearm injury.

Meldonium, also known as mildronate, is a Latvian-manufactured drug popular for fighting heart disease in former Soviet Union countries. Several athletes have tested positive for the drug since it became illegal in January, including two Ukrainian biathletes and Russian cyclist Eduard Vorganov. Earlier Monday, Russia's Ekaterina Bobrova, a European champion ice dancer, told local media she had tested positive for meldonium.

Sharapova has 35 career singles titles and over $36 million in career earnings.

Sharapova is currently No. 7 in the WTA rankings after playing just three tournaments and the Fed Cup final in the last eight months since Wimbledon due to injuries. She dropped out of the upcoming BNP Paribas Open in Indian Wells last Thursday, citing injury.

Sharapova also is thought to be the world's highest-paid female athlete due to her extensive business ventures and endorsement deals. Forbes estimated her earnings at $29.5 million for 2015, with $23 million from off-court ventures.

Sharapova has been among the best players of her generation since bursting onto the scene as a 17-year-old Wimbledon champion in 2004, beating Williams in the final. She won the U.S. Open in 2006 and the Australian Open in 2008 before finally completing the career Grand Slam with French Open titles in 2012 and 2014.

She became the world's top-ranked player in August 2005 and held the ranking five times for 21 weeks during her career. While she never came close to matching Williams' 21 Grand Slam titles, her five Grand Slam titles rank behind only Serena and Venus Williams among active players.

Sharapova was born in Russia and lived briefly in southern Sochi before moving to Florida as a child to begin her tennis career. She lives primarily in the Los Angeles area now.