The International Tennis Federation has confirmed that Marin Cilic has been banned for nine months for a doping violation.
The 24-year-old Croatian, who is ranked 24th in the world, tested positive for the banned substance nikethamide at the Munich Open in April.
However, the ITF has ruled that Cilic inadvertently took the substance "through his ingestion of Coramine glucose tablets that had been purchased on his behalf from a pharmacy".
The suspension, which is backdated from when he gave the original sample, is due to expire on January 31.
The length of the ban will see Cilic miss the Australian Open at the start of next year.