Serbian tennis player Viktor Troicki has received an 18-month ban for failing to provide a blood sample during a drugs test.
The International Tennis Federation took severe action against the former world No 12 after ruling that Troicki flouted their Anti-Doping Programme at the Monte Carlo Masters in April.
Troicki claimed he asked permission to miss the blood test as he was feeling unwell, but the ITF did not accept this explanation.
"Mr Troicki provided a urine sample, but did not provide a blood sample," said an ITF statement.
"He asserted to an independent tribunal that he was assured by the doping control officer (DCO) that it would be acceptable not to provide a sample on account of him feeling unwell that day.
"However, the tribunal concluded that the DCO told Mr Troicki that she could not advise him as to whether his reason for not providing a blood sample was valid, and that no such assurances were given by her.
"The tribunal determined that he is suspended from participation for a period of 18 months, and so ending at midnight on 24 January 2015."
The 27-year-old, who helped Serbia win the Davis Cup title in 2010, is suspended until January 24, 2015.