Rafael Nadal has denied that he ever used a banned substance to aid his performance and speed up his recovery time.

The 14-time Grand Slam champion was asked for his reaction to the news that Maria Sharapova had failed a drugs test at this year's Australian Open.

“I have never had the temptation of doing something wrong,” the 29-year-old said.

“I believe in the sport and the values of the sport.

“It is an example for the kids and if I am doing something that goes against that, I will be lying to myself, not lying to my opponents.”

Over the years the Spaniard has been the subject of some speculation regarding his ability to recover quickly between events.

Meldonium, the substance found in Sharapova’s drug test, is designed primarily to treat heart problems and the early onset of diabetes, but has side effects which include an ability to train longer and recover quicker.

Nadal has never failed a drugs test, however in 2011, former French Open champion Yannick Noah wrote a newspaper article saying Spanish sporting success was due to doping.

A year later, a satirical French TV show featured a life-size likeness of Nadal filling up his car’s gas tank from his own bladder before being pulled over by traffic police for speeding.

Then in 2013, Belgian former professional player Christophe Rochus questioned Nadal being able to dominate the 2012 French Open and then be injured two weeks later at Wimbledon.

The Spaniard has said that he used a treatment often known as ‘blood spinning’ to deal with his knee problems.

“With stem cells, I used it two times on my knees and it worked very well. I am not doing, never did, and never going to do something wrong.”

Nadal added that he trusts a doctor to monitor what medication he takes.

“He has been the doctor for all the Spanish players for a number of years,” he said. “I would never take nothing that he doesn’t know about.”