Maria Sharapova's failed drugs test lost her a $12.5 million a year deal with Nike

Maria Sharapova lost her lucrative deal with Nike on Monday night after she admitted testing positive in a drugs test for the recently-banned substance meldonium. The Russian's contract was worth at least $12.5 million a year.

UK-based sports marketing and sponsorship consultant Nigel Currie told Business Insider the deal was worth an estimated $100 million over eight years - Nike's biggest deal for a female athlete. There were likely bonuses tied into the deal too, although no details on these have been published.

Sharapova is the world's highest-paid female athlete, earning $29.7 million in prize money and endorsements between June 2014 and 2015, according to Forbes.

In a statement, Nike said: "We are saddened and surprised by the news about Maria Sharapova. We have decided to suspend our relationship with Maria while the investigation continues. We continue to monitor the situation."

Sponsors now react immediately to athlete scandals

In recent years, sponsors react much quicker to athlete scandals than they used to, according to Currie.

"A few years ago, sponsors would have said and done nothing until the dust had settled and the story had died down. Now they react immediately and almost add fuel to the story. Huge decision for them. The deal with Nike is the biggest for a female athlete and it is likely that some of her other sponsors will review their agreement with her," Currie said.

Sharapova also has endorsement deals with Avon, Porsche, Tag Heuer, Evian, and Tiffany.

On Monday night, Sharapova held an emotional press conference in Los Angeles in which she admitted she failed a drugs test at the Australian Open in January, where she lost to Serena Williams in the quarter finals.

Sharapova said she had been taking meldonium since 2006 due to a variety of health concerns, including the possibility she may have diabetes because it runs in her family.

The World Anti-Doping Agency (WADA) added meldonium to its list of banned substances at the start of 2016, but Sharapova said she failed to read the update.

"I made a huge mistake. I let my fans down and I let the sport down. I take full responsibility for it. I know that with this I face consequences and I don't want to end my career this way," the five-time Grand Slam winner said at the press conference.