Luxury watch-maker TAG Heuer and German sports-car brand Porsche joined Nike Inc. in suspending their relationship with Maria Sharapova after the world's highest-paid female athlete admitted failing a drug test.
Russia's Ms. Sharapova, considered one of the best female tennis players of her generation, said in a Monday news conference in Los Angeles that she had been taking meldonium for health reasons for a decade and had not noticed when it was banned by the World Anti-Doping Agency as of Jan. 1. She has been provisionally suspended by the International Tennis Federation effective March 12.
Failing the test led Nike, which has worked with Ms. Sharapova for more than a decade, to suspend its relationship with the 28-year-old, said spokesman Kejuan Wilkins. The test result could cost Ms. Sharapova a spot at the Rio 2016 Olympics, the $298,000 she won in January at the Australian Open, and more in endorsement deals.
"Nike has fanned the flames and other sponsors will be considering their position," Nigel Currie, the founder of sports marketing agency NC Partnership, said by e-mail. "There are very few female athletes who are recognized in every country, but she is one of them which makes her very attractive to global brands."
Nike, the world's largest sporting-goods company, is "saddened and surprised" by the news, said Mr. Wilkins. Her 2010 deal with the sportswear maker was said to be worth $70 million over eight years, according to a person with knowledge of the contract at the time.
LVMH-owned TAG Heuer, which Ms. Sharapova has represented since at least 2005, said it's suspending negotiations to renew a contract with the athlete that expired in December. The watchmaker also took down Ms. Sharapova's ambassador page from its website.
Volkswagen AG-owned Porsche, for which the tennis player had been brand ambassador since 2013, said: "Until further details are released and we can analyze the situation, we have chosen to postpone planned activities."
Ranked No. 7 by the Women's Tennis Association, Ms. Sharapova earned $29.7 million in 2015, making her the most highly paid female athlete in the world, according to Forbes, and No. 26 overall, just ahead of Arizona Cardinals quarterback Carson Palmer.
Just 23% of her prize money came from tennis winnings -- the other $23 million was earned from endorsements from companies including Avon Products Inc. and Danone SA-owned Evian bottled water.
A handful of athletes, including a Russian cyclist and six Georgian wrestlers, have tested positive for meldonium this year. According to International Tennis Federation Rules, a positive drug test at the event "automatically leads to disqualification of the results obtained by the player," including loss of titles and prize money.