At least three sponsors have now distanced themselves from Maria Sharapova after the tennis great admitted Monday to failing a drug test at the Australian Open in January.

The Porsche AG division of Volkswagen AG and the TAG Heuer SA subsidiary of LVMH Moet Hennessy Louis Vuitton SE said Tuesday they were suspending their marketing relationships with the five-time Grand Slam champion, according to news reports. The luxury brands follow in the footsteps of Nike Inc., which said Monday it was suspending its relationship with Sharapova.

The 28-year-old Russian tennis player was the world’s highest-paid female athlete in 2015 for the 11th straight year. Forbes estimated she earned almost $30 million, the bulk of which came from deals with sponsors such as sports apparel giant Nike and sports equipment company Head NV as well as Porsche, the German sports car maker, and TAG Heuer, the Swiss watchmaker.

Sharapova announced at a press conference Monday that she tested positive for the drug meldonium, which improves blood flow, at the Australian competition. The athlete said she had been taking the drug since 2006 for health issues — including the flu, irregular heart tests and signs of diabetes — and had not been aware the World Anti-Doping Agency added the drug to its list of banned substances this year. GettyImages-506777236 Maria Sharapova hits a backhand shot in her quarterfinal match against Serena Williams at the 2016 Australian Open in Melbourne Jan. 26. Photo: Cameron Spencer/Getty Images It’s unclear if and when Sharapova, ranked No. 7 in the world, will play again.

“I made a huge mistake, and I let my fans down, I let the sport down that I’ve been playing since the age of 4 that I love so deeply,” she said via ITV.

Sharapova had been a brand ambassador for Porsche since 2013. She was scheduled to appear at the Porsche Grand Prix tennis event in Stuttgart, Germany next month. “Until further details are released and we can analyze the situation, we have chosen to postpone planned activities,” a Porsche representative told Bloomberg News.

The tennis star, who was under contract with TAG Heuer until the end of last year, had also been in talks with the watchmaker to extend the partnership. “In view of the current situation, the Swiss watch brand has suspended negotiations,” a representative told the Wall Street Journal.