Sponsors Act Over Sharapova's Failed Drug Test

Three of Maria Sharapova's top sponsors have cut ties after her admission that she failed a drugs test at the Australian Open.

The US sportswear giant Nike (Sao Paolo: NIKE34F.SA - news) announced it will suspend its relationship with the tennis star while her use of the substance meldonium is examined by the International Tennis Federation (ITF).

Swiss watch brand Tag Heuer said it has decided not to renew its contract with the Russian, while Porsche has decided to postpone "planned activities" with Sharapova "until further details are released and we can analyse the situation".

Other sponsors could follow suit - Sharapova also enjoys deals with the likes of American Express (Swiss: AXP.SW - news) and Evian.

Announcing the failed test on Monday, the 28-year-old said she had been taking meldonium to treat a magnesium deficiency and early signs of diabetes for a decade - and the substance was only banned by the World Anti-Doping Agency (WADA) on 1 January.

:: Sharapova Drug Controversy: Meldonium Explained

Meldonium was banned because it can enhance oxygen uptake in the body and endurance.

The drug's manufacturer said on Tuesday the usual course of treatment is four to six weeks, and that rather than enhance an athlete's performance in competition, meldonium might actually do the opposite.

Sharapova's lawyer, John Haggerty, said her client was "completely stunned" when she received the letter notifying her of the failed drugs test.

Mr Haggerty said: "Because she had taken it for so many years, and it was okay year after year, it just got off the radar."

Sharapova has been provisionally suspended by the ITF.

:: Brand Sharapova: Highs And Lows Of Tennis Ace

The ITF's anti-doping programme suggests athletes who fail a drug test should receive a four-year suspension - but players who are not significantly at fault, or those who have never offended before, could see this reduced by 50%.

Former WADA president Dick Pound told Sky News he had little sympathy for Sharapova because athletes were sent a notice of the rule change and "for reasons unknown she chose to ignore that".

"There is a responsibility on the part of any athlete to know what's going into the body," he said.

The president of the Russian tennis federation, Shamil Tarpishchev, told the country's TASS news agency he expects Sharapova to play at the Olympics despite the failed test, describing the situation as a "load of nonsense".

Jeff Tarango, who coached the former world number one before she started taking meldonium, also had a level of sympathy, telling Sky News: "She (Munich: SOQ.MU - news) did get sick quite often and her heart wasn't quite good enough to play longer than 15-20 minutes at a time. The symptoms were there.

"The team around her didn't do their due diligence. She has to be wondering if her staff are going to 11 for her."