Richard Ings, a former chief executive of the Australian Sports Anti-Doping Authority, said in an email Monday that “the smart story here is how Sharapova missed the memo of it being banned; she has a massive support team.”

“I think it’s very important to have a great team around you with coaches and doctors, but at the end of the day, everything you do is on you,” she said.

Russia has been one of the epicenters of the doping scandals that have rumbled through global sports of late. Its track and field athletes were suspended from international competition in November and may not be reinstated for the 2016 Summer Olympics.

Sharapova, though she continues to represent Russia, has been based in the United States since age 7, although she has, by her own admission Monday, been taking medication for a decade that is not approved in the United States.

“I’m pretty sure if this was a track and field athlete they’d be getting a much rawer deal than Sharapova,” Kelly Sotherton, the former British heptathlete and 400-meter runner, said in a Twitter message Monday.

Under the rules of tennis’s antidoping program, Sharapova’s positive test would not normally have been announced by the I.T.F. until the adjudication process had been completed. But she decided to make her case public and Haggerty said she did not intend to request that her B sample be tested.

“I thought it was very important for me to come out and speak about this in front of all of you, because throughout my long career, I have been very open and honest about many things,” she said. “I made a huge mistake, and I’ve let my fans down. I’ve let this sport down that I have been playing since the age of 4 and that I love so deeply.”