Čilić tested positive for the banned substance nikethamide at a tournament in Munic in March and was later suspended by the International Tennis Federation (ITF).

But he appealed the ban to the Court of Arbitration for Sport (CAS) claiming he had inadvertently consumed the substance when a teammate had given him a glucose supplement bought from a pharmacy.

"Unbeknownst to me, the glucose tablets contained a substance that is banned in-competition [although it is allowed out-of-competition]," said Čilić. 

"I wish to emphasise that I have never knowingly or deliberately taken any banned substances in my life and that I am opposed to any use of performance-enhancing substances in sport."

On his appeal, the CAS released a statement claiming the ban imposed on Čilić by the ITF was too severe for the degree of fault committed.

"The Panel determined that the degree of fault committed by the athlete was inferior to that established in the [tribunal] decision," the CAS said.

"The Panel also determined that the sanction imposed was too severe in view of the degree of fault and concluded that it should be reduced to four months."

The reduced ban means that Marin Čilić can play in next weeks Paris Masters