At Wimbledon Čilić pulled out before his second round match claiming he had a left knee injury where he was scheduled to play Kenny de Schepper of France. However, a month later it was revealed that Čilić had pulled out due to failing a drugs test in Munich for, according to Jutarnji list daily, "incautious use of glucose." On 16 September 2013, he received a backdated nine-month ban due to testing positive for the banned substance nikethamide. Čilić claimed that the banned substance was ingested via Coramine glucose tablets bought at a pharmacy by a member of his team, and as a result the independent tribunal believed that he did not intend to enhance his performance. The suspension ran until 1 February 2014 and all prize money and points since the positive test including the Munich tournament were null and forfeited. Čilić appealed against this ban to the Court of Arbitration for Sport, who reduced the ban from nine months to four months on 25 October. They stated that "the degree of fault committed by the athlete was inferior to that established in the (tribunal) decision and the sanction imposed was too severe in view of the degree of fault". Čilić, whose ranking had dropped to number 47, received an immediate boost as results at the French Open, Queen's and Wimbledon were reinstated.