Sharapova gave at least seven out-of-competition and three in-competition samples throughout the year.

The Russian revealed in March 2016 that she had tested positive for meldonium at the 2016 Australian Open and was subsequently handed a two-year suspension by the ITF.

This was then backdated to January 26, 2016, and reduced to 15 months by the Court of Arbitration for Sport in October 2016.

Sharapova's suspension finished on April 26, 2017, and she subsequently made her comeback at the Porsche Grand Prix in Stuttgart just a few days later.

She reached the semi-finals in the German city after being given a wildcard entry.

She was one of numerous athletes to fail a drugs test for meldonium, a heart attack medication which was only outlawed by the World Anti-Doping Agency from the start of the 2016.

Her case was the most high profile due to her stature in tennis, where she has won five grand slam titles and an Olympic silver medal.

Doubts have since been cast about how long meldonium, which is said to boost endurance, remains in an athlete's system.

Two other Russian players, Svetlana Kuznetsova and Daria Kasatkina, were also subject to more than seven doping tests in 2017 whilst Ekaterina Makarova and Elena Vesnina submitted over 14 samples.

Denmark's Caroline Wozniacki, the current world number one, was also subjected to more than 14 tests.

In men's tennis, Switzerland's Roger Federer, Spain's Rafael Nadal and Croatia's Marin Cilic also submitted more than 14 tests.

Russia's highest ranked male tennis player, Andrey Rublev, who is ranked 31 in the world, passed more than seven doping tests in 2017.