In this Aug 22, 2006 file photo, tennis star Maria Sharapova poses outside of Bloomingdale’s in New York, before launching her new TAG Heuer watch. (AP)

INDIAN WELLS, Calif, (Agencies): Agnieszka Radwanska said she was “shocked, like everyone else” when Maria Sharapova revealed Monday that she failed a drug test in January at the Australian Open.

“It was a very sad day for tennis, that’s for sure,” Radwanska said Wednesday at BNP Paribas Open at The Indian Wells Tennis Garden. Petra Kvitova and Simona Halep used much the same words while discussing Sharapova’s positive test for the drug Meldonium.

Sharapova said she had been taking the drug since 2006 to help deal with a magnesium deficiency and other health issues, but wasn’t aware the World Anti-Doping Agency had added it to the list of prohibited substances this year because she hadn’t looked at the updated list.

Halep, the defending women’s champion in the Indian Wells event that started Wednesday, called it “a tough moment for the sport, a bit disappointing,” and Kvitova said “I hope it will not affect the tennis world. I hope that the fans will still like tennis.” Men’s star Rafael Nadal termed it “terrible for the world of sport in general and for our sport especially.”

“It’s terrible because the sport must be clean and must look clean,” Nadal said. “We have a good anti-doping program and the players who are not doing the right things are going on trial, so we will see how it goes.”

Nadal said he lets his doctor keep track of the changes on the prohibited substance list and is “100 percent confident with my team” and knows everything he is taking. But he also knows that nothing is foolproof.

“It’s difficult to imagine that something like this can happen, but there’s always mistakes. Everybody can have mistakes. I want to believe that for sure it’s a mistake for Maria, she didn’t want to do it, but there’s always (the possibility) that it’s negligence.

Meanwhile, Maria Sharapova’s racket supplier became the first main sponsor to publicly back the five-time Grand Slam champion after she admitted to failing a doping test. Austria-based company Head announced Thursday it was planning to extend its sponsorship deal, three days after Sharapova revealed her use of the banned substance meldonium.

Head CEO Johan Eliasch said Sharapova has made “a manifest error” by her continued use of the drug after it was banned, but added there was no “evidence of any intent by Maria of enhancing her performance or trying to gain an unfair advantage.”

Eliasch said his brand, which started sponsoring Sharapova in 2011, “is proud to stand behind Maria, now and into the future and we intend to extend her contract. We look forward to working with her and to announcing new sponsorships.”

In related news, Coming to the defense of Maria Sharapova and others caught using meldonium, Russian Foreign Minister Sergei Lavrov said Thursday the drug never should have been banned.

Lavrov, echoing comments made by the inventor of the drug, said it was “a very strange decision, according to expert opinion” to put meldonium on the list of banned substances.

“In recent days there has been no limit at all to comments from specialists, including the inventor of this substance,” Lavrov told Russia’s Ren TV. “They clearly and professionally explain that it isn’t doping at all but a normal method for supporting the body and its basic functions.”

The World Anti-Doping Agency said meldonium was banned because there was evidence it enhanced performance and was being widely used in sports.

Lavrov, however, demanded that WADA present more evidence to prove that meldonium did enhance performance while suggesting the drug’s Soviet origins could have led to prejudice against the substance.

“The recent situation raises a lot of questions when a flurry of bans and accusations has been aimed at our leading, great athletes,” he said.

The man who headed the doping investigation that led to Russia’s suspension from global track and field sees little evidence that the country is doing enough to win reinstatement in time for the Olympics in Rio de Janeiro.

Former World Anti-Doping Agency president Dick Pound told The Associated Press on Wednesday that Russia is running out of time to clean up its drug-testing program in order for its athletes to able to compete at the games in August.

“There has been a lot of bluster and blanket denial and saying, ‘You are picking on Russia,’ that sort of thing,” Pound said. “I can’t tell for sure whether they are taking this really seriously or they assume the problem will go away.”

In related development, With no national anti-doping agency to collect samples and no laboratory to test them, the number of drug tests in Russia has declined so far this year.

The Russian Anti-Doping Agency was suspended late last year after an independent investigation accused the body of helping to cover up positive tests. The same probe, conducted by a World Anti-Doping Agency commission headed by Dick Pound, led to Russia being kicked out of global track and field -- possibly including the Olympics in Rio de Janeiro.

Because of the suspension of the national agency, known as RUSADA, there was a three-month window of sharply reduced testing before UK Anti-Doping began to collect samples around Feb 20, acting RUSADA director-general Anna Antseliovich told The Associated Press.

Latvia expressed sadness on Wednesday over the banning of the drug that has cast a pall over the career of tennis star Maria Sharapova, describing it as “one of the most significant accomplishments” of the tiny nation’s scientists.

The five-time grand slam champion has revealed she tested positive in January for the drug meldonium, which its Latvian inventor once said had been used to toughen up Soviet troops fighting at high altitudes three decades ago.

Latvia, a Baltic nation of under 2 million people that won independence from the Soviet Union in 1991, is relatively unknown to outsiders apart from visitors who use the capital Riga as a destination for partying.