Maria Sharapova has admitted that she failed a drugs test at the Australian Open earlier this year.
The former Wimbledon champion, 28, revealed that she has been taking medicine including a substance called meldonium during the last 10 years - but that the substance was placed on WADA's banned list from January 1 this year.
That information was made readily available to competitors via a letter - declaring the changes to the banned substances list for 2016 - which Sharapova admits receiving on December 22, but not reading.
"I take great responsibility and professionalism in my job every day. I made a huge mistake. I've let my fans down, I've let this sport down," said the Russian on Monday evening.
"I know that with this I face consequences and I don't want to end my career this way and I hope that I will be given another chance to play this game again.
"I received a letter from the ITF that I failed a drugs test at the Australian Open," said Sharapova. "I take full responsibility for it. "For the past 10 years I have been given a medicine called mildronate by my family doctor and a few days ago after I received the ITF letter I found out that it also has another name of meldonium which I did not know.
"It is very important for you to understand that for 10 years this medicine was not on WADA's banned list and I had legally been taking the medicine for the past 10 years.
"But on January 1 the rules had changed and meldonium became a prohibited substance which I had not known."
Sharapova has stated that she will co-operate with the International Tennis Federation's investigation.
"I only received the letter a few days ago and I will be working with the ITF."