A tip from a confidential source to the U.S. Anti-Doping Agency in March 2014 that Eastern European athletes were using the drug meldonium as a performance enhancer triggered the doping scandal that now has ensnared Maria Sharapova, a person with knowledge of the process told USA TODAY Sports.

The person was not authorized to discuss the topic publicly.

Acting on the information, USADA, the organization that brought down Lance Armstrong, added a talk about meldonium to the agenda of its 2014 annual symposium in Phoenix.

By late October 2014, the drug was added to the World Anti-Doping Agency’s monitoring list.

Next came the testing of stored urine samples in late 2014, funded by the Partnership for Clean Competition. An analysis of 8,300 random urine samples revealed that 182 (2.2%) contained meldonium, according to a study in late January 2015. All of those were Eastern European athletes.

The eye-opening results of the study were published online in April 2015, and were the basis for WADA adding meldonium to its list of banned substances in October 2015, to go into effect January 1, 2016.

Almost exactly two years after USADA first heard about the drug, Sharapova was announcing in a Los Angeles hotel that she had tested positive for it.​